Tyler Cowen scoots the saucer of smoky Chinese chicken over by the guo tie pot stickers, but the waitress still can't find homes for the flaky thousand-layer pancake or the bowl of xue cai ro si mian -- noodle soup with shredded pork and mustard greens.

She could just squeeze the dim sum plates into the corner of Cowen's little table at Annandale's A&J Restaurant, except that's where he stowed the shredded bean curd and gooey boiled peanuts when the cai ro wonton arrived five minutes ago.

This is Tuesday night for Cowen, a 39-year-old economics professor at George Mason University who writes about ethnic cuisine for fun.

"I'll order something just to try a bite of it," Cowen explains on his fourth trip to A&J in seven days. "Once I've been to a restaurant five times, I don't try things as much."

Cowen will return to A&J (4316 Markham St., Annandale; 703-813-8181) for another dinner the next night after Colombian chicken in the afternoon. Thursday will be a Thai lunch and sushi dinner. Friday: Indian and Vietnamese. Then Indian again, Middle Eastern, Turkish, Chinese and Thai. All of which is taking Cowen away from his latest hot spot, a fish-and-chips restaurant near his Falls Church home that specializes in Persian.

Cowen's pace through Washington's ethnic restaurants may seem frantic, even in a region enamored with foreign food. But his approach -- analytical, methodical and often solitary -- is distinctly academic. So is the goal: publication.

Tucked into an obscure corner of the George Mason Web site, "Tyler Cowen's Guide to Ethnic Dining" offers short, breezy and sometimes catty reviews of 231 area restaurants spanning 73 cuisines.

"Exactly the sort of place you don't expect to find in Northern Virginia. Real Wiener Schnitzel, for one thing," Cowen writes of Alexandria's Cafe Monti (3250 Duke St., Alexandria; 703-370-3632). "The food has a strongly European feel, yet the place looks like a bit of a dive."

For a decade, Cowen has quietly eaten his way through Washington's rise to the top tiers of ethnic cuisine -- employing his generous appetite and economist's eye to follow the climb.

"Restaurants manifest the spirit of capital multiculturalism," he writes in the first line of his 14,000-word guide, which can be found at www. gmu. edu/ jbc/Tyler/ethnic.html. "Entrepreneurship, international trade and migration, and cultural exchange all come together in these communal eateries."

He's a man who makes no apologies for bringing the hunt for a good tamale to the brink of footnote citations.

"I think of it as more than a list," the professor with a Harvard doctorate explains at dinner, projecting his voice as if sophomores might be dozing in the back row. "I think of it as a guide on how to think about food."

Evaluating a Trend

Heat lamps don't bother Cowen, which is why he's back to prowling the twin 25-foot spans of lunch offerings at a suburban Indian buffet.

This is his second plate today at Minerva, a bright, high-ceilinged restaurant that competes with Hooters in a Fairfax strip mall. Cowen has been here 10 times since Minerva (10364 Lee Hwy., Fairfax; 703-383-9200) opened in January, but the squash curry is new to him this afternoon. A big spoonful of it goes on his plate for Round 2, along with more curd rice, vegetable raita, ginger chicken and coconut chutney, which Cowen declares "a knockout."

"Indian food is the best buffet food around," he explains from his green vinyl booth. An Indian musical rolls silently on a movie screen above the food bars. "A lot of Chinese places do buffets, but it doesn't work well because Chinese food is cooked quickly at high heat. But Indian food is perfect; it's simmered for long periods of time."

Cowen also tracks arcs of food popularity. Once mainstream diners embrace an ethnic cuisine, he says, the food usually back-steps into blandness as a sop to the American palate. Before the crossover, when mostly immigrants are eating the food, menus remain authentic but not ambitious.

The best cuisines straddle the two phases.

"The time of the cusp is very exciting," Cowen explains. "It's still rooted in the older ideas of the cuisine. It hasn't sold out yet. At the same time, all the new customers are encouraging new places to open up. Chefs are experimenting with new techniques. There's more competition."

His current cusp list: Afghan, Indian and Vietnamese. "I don't think Bolivian is yet cusp. Ethiopian is an odd mix; some places quite crossover, other [restaurants] are just for Ethiopians," he says. "Cusp candidates are rare, though, by their nature."

Cowen doesn't realize he's fallen on the wrong side of Minerva's own private cusp.

The $7.95 buffet deal there draws a decent office crowd for lunch, so the kitchen tones down the spiciness during the week. That's when Cowen goes. But the hotter, ultra-authentic fare only comes out on weekends, when the customers are mostly Indian.

"We make it more ethnic," explains manager Siddhartha Adepu, 37. "That gives us a homemade taste."

Cook Tours

His black, thinning hair brushed forward, Cowen doesn't look quite his 39 years. His appetite certainly doesn't reflect his build -- a bit soft in the middle, but no heft and no paunch. Cowen credits pick-up basketball played badly and an indifference to alcohol and sweets.

Divorced several years ago after a four-year marriage, Cowen gets almost self-righteous when it comes to his love of cooking. He scoffs at salt and pepper and sautes whole spices for his lamb curry and Thai coconut chicken.

"Anything ground, I just won't eat it," he says. "It's a crime."

Yet Cowen seldom dines at home. He swears it has nothing to do with the purple-sequined voodoo idol hogging a counter in his modest kitchen. It's one of hundreds of pieces of Haitian and Mexican folk art he has scattered throughout his 1950s ranch-style home -- perched on walls, spread across tables, stacked 10 deep on the carpeted floor.

Cooking just takes time. Besides, he gets antsy.

"I don't go to a lot of parties. I'm not a social person. But I do like to go out. . . . I like being in the restaurant, sharing the experience," says Cowen, who usually lunches with colleagues and dines with library books. "It's not like we live in a European city. We're not real strong on public places. The restaurant serves that role."

Notable Quotable

Cowen carved himself a niche in academia with a brazenly anti-intellectual move: embracing the celebrity culture as a boon for the arts.

His book "In Praise of Commercial Culture" (Harvard University Press, 1998) argues that the entertainment industry actually produces masterful work (The Beatles, "Seinfeld") and also spurs interest in more high-brow creations.

A film buff who loves Iranian cinema, Cowen still thinks Jennifer Lopez has a knack for landing smart roles. He published a piece in Canada's National Post defending Napster. Reporters call him when they need academic heft for their "Survivor" stories.

A critic once panned a Cowen book as "unpersuasively optimistic," but Cowen insists that consumer markets ultimately raise standards. Even at dinner.

"There's restaurants that lots of people go to, and restaurants that only the elite go to, and we don't have to choose which is the best food," says Cowen, who plunks down $130 for his annual meal at the Inn at Little Washington and mourned fine dining in the District when Jean-Louis closed. "There's no [National Endowment for the Arts] that subsidizes good food. Yet we have a wonderfully diverse selection."

Noted, With Reservations

For all its economic grounding, Cowen's dining guide would wither under much scholarly review. He will pan a restaurant after one visit or a mere look at the menu, and recommend another on a hunch.

But most of the critiques seem more informed -- Cowen scoring a series of meals against his knowledge of the cuisine. A tenured professor with research subsidies and the summers off, Cowen has traveled to 60 countries and every continent but Antarctica.

"Highly authentic, too authentic some would say," Cowen writes of the Japanese Temari Cafe (1043 Rockville Pike, Rockville; 301-340-7720). "If pork cutlet doused in ketchup is your thing, this is the place to go."

He critiques Washington's toughest reservations, though Cowen prefers the dives.

"Tyler's not after the experience most people go to restaurants for," said Randy Kroszner, 38, who teaches at the University of Chicago business school and is one of Cowen's two high school buddies who also became economics professors. "The settings are completely secondary."

Cowen never takes notes, writing his reviews from memory. They're pointed: "Seems more like a yuppie drinks place."

And puckish: "Cafe Atlantico was once well-known for attracting the most beautiful women in Washington, but this is no longer the case."

And passionate: "Haitians are among the world's most creative people, and this restaurant shows that."

"I think in order to learn, you have to write," Cowen explains over pupusas at Atlacatl (4701 Columbia Pike, Arlington; 703-920-3680). "Some of my theories on food, I really had to sort them out and refine them when I sat down to write my food guide."

The guide started as a list of his favorite restaurants near the University of California at Irvine, where he started his teaching career in 1987.

Cowen grew up in the suburban predictability of northern New Jersey in the 1960s. His father ran the local chamber of commerce, and his mother cooked spaghetti for Cowen and his older sister.

Cowen didn't even like Chinese takeout until after college. But some of Cowen's Harvard friends dragged him to a few ethnic restaurants and the menus intrigued him.

A year studying in Europe sealed it. With an entire continent's cuisine at his disposal, Cowen "just went crazy." He still says Swedish pizza beats all the rest.

Back at Irvine, within orbit of Los Angeles and its ethnic riches, Cowen got lost trying to retrace his steps to a new discovery. So he typed up a list of addresses with a few comments to jog his memory.

Then some colleagues asked for copies. They gave it to friends. Eventually, Cowen wrote an update. By the time he left for George Mason in 1989, the list had morphed into a guide.

He started a new restaurant list at the start of a decade that would see waves of immigrants upend Washington's demographics and turn the region into one of the country's top destinations for the foreign-born.

Almost 90 percent of the 250,000 immigrants who arrived here legally in the 1990s settled in the suburbs, bucking the historical trend of urban migration, according to a recent study by the Brookings Institution. They came from 193 countries and spread themselves across the regional map, rather than settling in the kinds of ethnic enclaves familiar to many cities.

The result: a burgeoning crop of ethnic restaurants dispersed scatter-shot throughout the suburbs, which energized Washington's conservative dining scene. Washington now ranks on the list of cities with great ethnic food, rosters that always start with Los Angeles and New York.

Today, ethnic restaurants account for about a third of the region's 7,000 restaurants, but are fueling as much as half of the industry's recent growth, according to Eric C. Peterson, president of the Restaurant Association of Metropolitan Washington.

"People are dining where they can find a better value" in a troubled economy, Peterson said. "Instead of going to the white-tablecloth steakhouse, they're going to the Thai place or the Indian place or the Afghan place."

Chance Encounters

Most of Cowen's picks are literal finds. He spots them while driving to the grocery store or another restaurant.

Though the guide covers the entire region, Cowen increasingly finds himself sticking to Northern Virginia's booming ethnic scene. So his expertise beyond the Potomac is constricting. He has no fellow ethnic-food buffs as friends, no one to compare notes with or exchange leads. A couple of readers e-mail him every month, usually with a suggestion.

"I use it all the time. It's better than Zagat's," said Doug Herbert, 48, a Connecticut Avenue lawyer who moved to the District in 1978 and stumbled onto Cowen's site. "It's odd that the most comprehensive restaurant guide in D.C. -- not the one that necessarily has the longest descriptions, but has the most off-beat restaurants -- is free."

Cowen updates his guide only twice a year, so some of his picks no longer exist. The Spartan site has no color, no links and no advertisements. George Mason says it received 230 hits last month.

Cowen funds his restaurant hobby with his $130,000 a year salary from George Mason, where he is director of the Mercatus Center for economic policy. The author of five books, Cowen says he's never pursued making money off the guide. Not that he wouldn't publish it; there just hasn't been any interest.

"I don't care," Cowen says toward the end of dinner at Atlacatl, his guide's pick for best Salvadoran food. "It's just fun to eat in this area. So many of the great places are undiscovered."

Leaving the mix of English and Spanish conversations inside Atlacatl, where framed restaurant reviews share wall space with beer posters, Cowen mentions another Salvadoran place he's been meaning to try.

In a cramped strip mall one block down Columbia Pike, Cowen approaches a windowless door under a darkened neon sign for "Restaurante El Salvador." Curtains and iron bars cover the windows flanking the entrance.

He pushes the door open to reveal a shiny and surprisingly long restaurant, with fake wood paneling and hanging plastic plants flicking brightness into the lack of natural light.

"I like the feel of this place," Cowen says. "We'll see."

First comes garlicky salsa with a sharper bite than the Atlacatl batch. Cowen points out that this place wraps its corn tamale in a husk. Then the pupusa, a tortilla stuffed with marinated pork and cheese, and Cowen's tasting crucible for Salvadoran food. The verdict: supple, juicy and delicate -- the best he's ever had.

"I come to a place like this, and that's when you know it's worth it to do a food guide," Cowen says after the waitress tells him, in Spanish, that Restaurante El Salvador (4805 Columbia Pike; 703-521-3225) opened 11 years ago. "A place as good as this, someone should be out there singing its praises."

He takes a breath.

"Here I'll say: 'The best pupusas around; excellent tamales; fresh, spicy and excellent salsa,' " he continues, riffing an impromptu write-up. " 'The best El Salvadoran place I know. Don't be put off by the exterior. Go.' "

Tyler Cowen, at Atlacatl in Arlington, samples ethnic cuisines.Tyler Cowen, a professor at George Mason University, offers his opinions of various restaurants online.