I love burritos. I'm a burrito brother. Literally. In 1989 I founded Burrito Brothers, Washington's first burrito place, so you'd think that by now I'd be an expert on the subject. I did know that burritos were made by wrapping a flour tortilla around any number of fillings, usually meat, beans, rice and salsa. While I was growing up in San Francisco, I knew them by the nickname "logs," a term of endearment for a healthful fast food that filled your stomach without emptying your wallet.

Then, a couple of years ago, my favorite food evolved into something different. Suddenly they weren't being called burritos at all. They were "wraps," and they were everywhere--except, it seemed, in Mexican restaurants. This got me wondering about the process of culinary evolution. Where did the original burrito come from? What did it taste like? Was it anything like what I knew as a burrito? After all, if a pollo asada burrito could turn into a grilled-chicken Caesar salad wrap overnight, who knew what evolution the burrito went through to become what we know it as today? I decided to find out.

In late June, I met up with Dana Ingersoll, a freelance photographer, and began a cross-country quest for the origin of the burrito. We were determined to trace its history through the people who know it best--the owners and operators of old burrito places. As we followed the historical trail, and got closer and closer to the source, the burritos became smaller and smaller, and our favorite ingredients disappeared one by one. When we finally found what we thought was the original burrito, it was very different from the burritos we knew and loved. The burrito's evolution seemed like a cross-generational version of the children's game of telephone, in which a message is passed through so many people that the message at the end is completely different from the original.

I must say upfront that this search was viewed with some skepticism by the many people with whom I spoke. Burritos are not considered worthy of study by serious students of Mexican cuisine. Many Mexican cookbooks do not mention burritos at all, or dismiss them as "Tex-Mex" or as an Americanized version of Mexican food. My questions were often met with looks that made me feel as if I had stepped into a diner in America to inquire in all seriousness about the origins of the tossed salad, or as if I had asked a hot dog vendor if he knew precisely why they were called "hot dogs." Here's what I found. San Francisco

San Francisco is the burrito capital of the United States. I got hooked on burritos there as a high-school kid. I was fascinated by the skill of the Mexican-born burrito makers. While their English was rough, their movements were smooth and precise as they spooned beans, rice and salsa into freshly steamed flour tortillas. With a quick flip, tuck and roll, the food was transformed into an edible cylinder of bliss wrapped in foil.

The best and oldest places are in San Francisco's Mission District, the neighborhood named for Mission Dolores, the Spanish mission built in 1776. It is a predominantly Latino neighborhood, and burritos are the food of the Mission. Ask any San Franciscan to name his or her favorite burrito place, and you will hear about El Toro, La Taqueria, Taqueria Can Cun, Taqueria La Cumbre, El Farolito, La Rondalla, Andele, Taqueria Pancho Villa, El Faro, Taqueria San Jose and many others. Everyone has a favorite, and each place has its specialty. My favorites are the chile relleno burritos at Pancho Villa, the bean and cheese burrito with fresh avocado at La Taqueria, and the vegetarian burrito at Taqueria Can Cun.

The first places to serve burritos here were La Cumbre on Valencia Street and El Faro on Folsom Street. Both were originally markets (El Faro was a grocery, La Cumbre a meat market) that began serving burritos and tacos in the late 1960s. A few years later, both places dropped their other operations to concentrate on the popular burritos.

Our first step was to talk to Raul Duran, owner of La Cumbre. He said he began selling burritos after a friend from Los Angeles told him that people there were making money selling them. (That made L.A. our next stop.) Duran first tried burritos in Tijuana, Mexico, but didn't remember ever having them as a kid growing up in a little Mexican town near the border near El Paso. He did, however, remember guys with carts or just a pot of cooked meat who sold tacos in the streets. "One guy would sell beef tripe, another pork, another tongue. They would make up a bunch of stuff at the beginning of the day, and then sell until it was all gone. Those tacos were fantastic." Duran changed his former meat market into a taquer{idotless}a because he was inspired by those street vendors. The tacos were small, typically just meat in a tortilla, and you would eat several to make a meal. (Almost by definition, tacos are made with corn tortillas, and burritos with flour tortillas. Tacos tend to be small because, given the lack of gluten in corn, there's a limit to how big corn tortillas can be.)

The burritos at Duran's La Cumbre and everywhere else in San Francisco, however, are big. Really big. Most of them weigh at least a pound, and at many places you can get deluxe burritos or superburritos that are even bigger. Typically, the burritos are made with a 12-inch flour tortilla that is either steamed or grilled, then filled with pinto or black beans (whole or refried), rice and fresh tomato salsa. You can then choose from several types of meats like carne asada (grilled beef), carnitas (slow-cooked pork), chicken (in green tomatillo sauce, red chili sauce or grilled), al pastor (pork cutlets stacked on a gyro spindle and sliced), chile verde (pork in green sauce), lengua (beef tongue) or cabeza (head). Extras like guacamole, sour cream, cheese, tomato, lettuce, cilantro and salsas from red to green and hot to mild can be added as well. Some of the larger places offer other foods like chiles rellenos, flautas, grilled shrimp, grilled green onions, and more.

The burrito here in San Francisco may have been infected with the American bigger-is-better syndrome. Duran told us that customers really like big burritos, and so that's what he makes. But that, remember, was just since the late '60s. We decided to move on to L.A., source of Duran's burrito inspiration and where we hoped to find evidence of earlier burritos. Los Angeles

L.A. does have an older Mexican "colonia" than San Francisco. The oldest continuously run Mexican restaurant there, opened in 1927, is El Cholo. They make a superb green corn tamale, delicate and light (made from sweet young corn and served only when corn is in season), but El Cholo didn't start serving burritos until the late '70s, well after the San Francisco places.

Olvera Street downtown has some great little Mexican places that date back to the 1930s. One of them, La Luz del Dia, makes corn tortillas by hand in the traditional way. When I walked in, I saw four or five Mexican woman rolling out the tortillas using a metate, a grinding stone made from volcanic stone. The food was great, but there were no burritos. The owner, Frank Cazares, explained that burritos are not part of most Mexican cooking because small corn tortillas, not flour tortillas, are popular in most of Mexico. Flour tortillas, he said, are popular only in Northern Mexico, in the state of Sonora in particular. He also said he knew of some popular places in Tijuana that served burritos. Sonora, Tijuana--Sonora sounded promising, but Tijuana was closer. I wondered where to go next.

The next day, I began asking around in East L.A., along Cesar Chavez Street, formerly Brooklyn Avenue, the heart of the oldest Latin neighborhood in the city. I was directed to a small place on Evergreen called El Tepeyac. It has served burritos since 1954, and the founder and owner, Manuel Rojas, greeted us, answered some questions and let us try his burritos. The place has a devoted following, and at lunch that day I met six people who said they'd been customers for 30 years or more. The burritos were a little different here. They were served on plates, not wrapped in foil, and could be ordered with sauce on top, which you would never find in San Francisco. They were just as big here, though. One of the burritos, Manuel's Special, weighed nearly five pounds! The burritos were not just big, they were tasty. All the ingredients were absolutely fresh, and the sauces were complex. The guacamole was wonderfully flavorful, and the beans were light.

Rojas and Lucy Martinez, our waitress (who has worked at El Tepeyac for 25 years), both said they first tried burritos in Tijuana. That was enough for us: We drove south and crossed the border. Tijuana, Baja California

In Tijuana, we met Ricardo Torres, a boxing trainer who is a friend of Miguel Hara, the owner of La Taqueria in San Francisco. Torres told us that the oldest and most famous burritos in Tijuana came from Restaurante del Bol Corona, which has several locations in town. We found one about a 10-minute drive from downtown, near the bullfighting ring. It was a small building with a carryout window and some high chairs set up at an outdoor counter.

The menu here was exclusively burritos, but these burritos were very different from the ones north of the border. They were about half the size of California burritos, and usually had only one or two ingredients inside. They were also folded differently: The meat-filled 12-inch tortilla was folded on a hot griddle into a flat rectangle, not the usual cylinder. Several kinds of beef were offered as fillings (carne asada, caldillo or stew, and machaca, made by boiling and shredding beef), pork (carnitas and chile verde), chicken (in red chilies), shrimp (grilled), lobster, and beans and cheese. There was no rice, no guacamole, no sour cream. There were two salsas, one hot and one mild, both excellent. The burritos were great, but different from what we were used to.

Restaurante del Bol Corona has a long history. It started in 1934 as a small bar with an eight-seat counter that served burritos as snacks. By the 1950s, it had added eight bowling lanes and had become an entertainment destination on Tijuana's Main Street (now Avenida Revolucion). That location popularized burritos in Tijuana and showed many future entrepreneurs that there was a future in the burrito business. It also allowed Restuarante del Bol Corona to expand, and open additional locations in Tijuana. Today Bol Corona also wholesales burritos to convenience stores, and has a factory that manufactures 60,000 flour tortillas a day.

The owner (and son of the founder) Leopoldo "Polo" Borquez, spent the morning with me touring his tortilla factory and talking burritos. He told me that his family came from Alamos and Navojoa in Sonora, where he thought burritos originated. He was certain that his father had been the first to serve burritos in Tijuana, and may have been the first anywhere to make shrimp and lobster burritos. This made our next step obvious. Hermosillo, Sonora

Sonora is just south of Arizona. Most of the state is an arid plain, dotted with saguaro cacti. The area is well suited to ranching and it is known for the quality of its beef. As we had been told to expect, flour tortillas were the norm here. They came in a wide variety of sizes and thicknesses, from very small (4-inch diameter) to the legendary tortillas sobacas, or armpit tortillas, which get their name because they stretch from the shoulder to the hand of the person making them.

In Hermosillo, the state capital, we found lots of street vendors serving burritos. In the main mercado, or market, several stalls made fresh flour tortillas, and several served burritos. The Hermosillo burritos were tasty and much like the ones we had seen in Tijuana, but none of the vendors or market proprietors knew anything about the burrito's origins.

As we left the market, we walked along a tree-lined street on a high sidewalk adjoining a park. We were disappointed--after all, this was the capital city of the state that we hoped was the birthplace of the burrito. Just as we were about to give up and move on to another city, we heard a voice call out to us in English, "Hey, are you guys looking for something? Maybe I can help you."

We looked over and saw a friendly-looking young man in a pickup truck looking over at us. "My name is Alberto," he called. "I'm visiting my parents here. Can I help you?"

We were a little guarded at first, but Alberto Munoz turned out to be our angel. He took us to Restaurant Xochimilco (so-chee-MEEL-ko), which has been in business for 49 years. It seats 300, and is Sonora's top restaurant.

The owner and founder, Poncho Durazo, is 80 years old and an authority on Sonoran cooking. Durazo told us that machaca burritos (the ones made with boiled, shredded beef) are the Sonora tradition. Before refrigeration, he said, beef was preserved by drying it in thin slices. Machaca is made by later pounding and cooking the dried beef back to tenderness. The word comes from the Spanish machacar, which means to pound or crush. Beef machaca was a staple for the miners, ranchers and cowboys who lived on these arid plains in the 19th century. Machaca burritos were an easily portable meal for these workers. The name "burrito" probably comes from an old Spanish saying, "If I had a horse, I would go make my fortune, but I only have a little donkey" (the Spanish for "little donkey" is "burrito").

Durazo makes his machaca and machaca burritos the traditional way, just the way his mother made them and her mother before that. So finally, we felt, we had found the holy grail and would taste the original burrito!

But when the burrito came out from the kitchen, we wondered if there had been some mistake. This humble burrito was very small--maybe 6 inches long and 1 1/2 inches in diameter, a far cry from the hefty burritos we were used to. The meat, while smoky and flavorful, was a little bit dry and chewy, as you might expect dried beef to be.

I was disappointed, but only for a moment: I realized that all was as it should be. I had found the original burrito, but I had also found out something more basic. Things change. Tastes change. Foods evolve. Each new cook interprets the past and creates a new riff on an old theme. The original may not be the best. It is not that new is better or that old is better, but that each interpretation may be valid for a particular time and place. For me, I'll stick with the California style any day. But that is my own bias. It's what I grew up on. So although I traveled far to make my discovery, I, like the burrito itself, eventually folded back on myself and came home to the old standby. Peter Fox reported on his burrito quest for National Public Radio this past summer. Photographer Dana Ingersoll recorded their month-long trek. Follow the Trail To follow Peter Fox's burrito trail you can use these addresses: San Francisco:

La Taqueria, 2889 Mission St., San Francisco, Calif. 94110; call 415-285-7117

Taqueria La Cumbre, 515 Valencia St., San Francisco, Calif. 94110; call 415-863-8205

Taqueria Pancho Villa, 3071 16th St., San Francisco, Calif. 94110; call 415-864-8840 Los Angeles:

El Cholo, 1121 S. Western Ave., Los Angeles, Calif. 90006; call 213-734-2773

El Tepeyac Cafe, 812 N. Evergreen, Los Angeles, Calif. 90033; call 213-268-1960

La Luz del Dia, 107 Paseo De La Plaza, Los Angeles, Calif. 90012; call 213-628-7495 Tijuana:

Restaurante del Bol Corona, Avenida Ocampo 729, Z.C., Tijuana, B.C., Mexico; call 011-52-66-38-44-29 Hermosillo, Sonora:

Xochimilco, Obregon No. 51, Colonia Villa de Seris, Hermosillo, Sonora, Mexico; call 011-52-62-50-40-89 The Makings of a Classic Burrito The following recipes make the components of classic beef or chicken burritos. To assemble the burrito: Steam or grill a 12-inch flour tortilla for 30 seconds to soften it up. Then spoon about 1/4 cup salsa, 1/2 cup rice, 1/2 cup beans and 1/2 cup meat down the center of the burrito. Fold 2 to 3 inches of the right and left sides in. Flip the bottom up over the filling, tuck it in and roll up the burrito. Cheese, guacamole, hot sauce or sour cream may be added to the filling as desired.

Pollo Asada

(Grilled Chicken)

(Makes enough for 4 burritos)

1 1/2 pounds boneless skinless chicken breasts

Salt to taste

2 to 3 limes

About 2 tablespoons vegetable oil

Preheat the grill or broiler.

Remove the skin from the chicken breasts. Sprinkle with the salt and lime juice to taste. Brush lightly with the oil. Grill or broil on both sides until cooked. Cut into 1/2-inch cubes. Per serving: 233 calories, 38 gm protein, 1 gm carbohydrates, 8 gm fat, 104 mg cholesterol, 2 gm saturated fat, 223 mg sodium, 0 gm dietary fiber

Carne Asada

(Grilled Beef)

(Makes enough for 4 burritos)

1 1/2 pounds skirt steak (flank steak can be substituted)

Salt to taste

About 2 tablespoons oil

Preheat the grill or broiler.

Trim all fat from the skirt steaks and pound until no more than 1/2 inch thick. Sprinkle with salt, brush with oil, and grill or broiler on both sides until cooked. Cut into 1/2-inch cubes.

Per serving (using flank steak): 324 calories, 41 gm protein, 0 gm carbohydrates, 17 gm fat, 71 mg cholesterol, 6 gm saturated fat, 220 mg sodium, 0 gm dietary fiber

Burrito Rice

(Makes enough for 12 burritos)

2 large tomatoes, chopped

2 medium yellow onions, chopped

4 cloves garlic, chopped

2 tablespoons corn or canola oil

2 cups long-grain white rice (not parboiled rice)

Salt to taste

4 cups water

Saute the tomatoes, onions and garlic in oil in a saucepan until the onions become limp and some of the moisture from the tomatoes has evaporated. Add the rice and salt, saute for a couple of minutes longer. Add the water, stir and bring to a boil. Reduce to a simmer, cover and cook for 20 minutes. Remove from the heat, stir to fluff the rice and allow to stand for a few minutes with the cover on. Per serving: 161 calories, 3 gm protein, 30 gm carbohydrates, 3 fat, 0 mg cholesterol, trace saturated fat, 183 mg sodium, 1 gm dietary fiber

Burrito Beans

(Makes enough for 12 burritos)

1 pound dried pinto or black beans

4 cloves garlic, peeled

1 medium yellow onion, chopped

2 tablespoons salt

Pick through the beans, discarding stones or dirt. Wash the beans three times. Place them in a large stockpot and cover with water (cover the beans by 2 to 3 inches). Discard any beans that float. Add the whole garlic cloves and the chopped onion. Bring to a boil, then cover and simmer for 1 1/2 to 2 hours until the beans are soft, but not quite done. Add the salt and continue simmering until the beans are tender and cooked, but not mushy. Per serving: 188 calories, 11 gm protein, 35 gm carbohydrates, 1 gm fat, 0 mg cholesterol, trace saturated fat, 536 mg sodium, 10 gm dietary fiber

Salsa Bandera

("Flag" Salsa)

(Makes enough for 12 burritos)

This salsa contains the red, white and green of the Mexican flag. The recipe comes from Nancy de Valenzuela at Ceneduria Somala in Alamos, Mexico.

3 large tomatoes, chopped very fine

2 medium white onions, chopped very fine

2 cloves garlic, chopped very fine

2 stalks celery, chopped very fine

6 jalapeno chili peppers or 1 medium cucumber

Oregano to taste

Salt and pepper to taste

Combine the tomatoes, onions, garlic and celery in a bowl. For a hot salsa, use the jalapenos with their seeds, chopped fine. For medium heat, remove the seeds from the chilies first. For mild salsa, substitute the cucumber, chopped fine, for the chilies. Season with a few dashes of oregano and salt and pepper to taste. Per serving: 40 calories, 2 gm protein, 8 gm carbohydrates, trace fat, 0 mg cholesterol, 0 gm saturated fat, 100 mg sodium, 1 gm dietary fiber CAPTION: On the quest for burrito beginnings, clockwise from left: El Tepeyac in East Los Angeles; Taqueria Pancho Villa in San Francisco's Mission District; Restaurante del Bol Corona in Tijuana, Mexico; Poncho Durazo, owner of Restaurant Xochimilco in Hermosillo in Sonora, Mexico, demonstrates the size of one of his tortillas sobacas (so-called "armpit tortillas"); and mariachis on Olvera Street in Los Angeles. ec CAPTION: A burro -- not a burrito -- in Alamos, Sonora, Mexico. ec