Baja California is a proving ground for tire tread and five-day deodorant. It's a true Mexican frontier that begins south of Catavina in the high central desert where you peel off from Mexico 1, the famous transpeninsular highway, and forget about telephones, newspapers, electricity and plumbing.

Six of us bounced the rocky back roads of Baja in a four-wheel drive GMC Sierra Classic outfitted with 20-gallon Igloos full of San Diego water, ice chests packed with fresh pineapples, mangos, papayas, avocados, artichokes -- and plenty of good Mexican beer.

A basket of tortillas, a bottle of salsa and thou. For what more could you ask? If we didn't have it on the truck we would find it at our destination -- our palm-thatched beach shack at Bahia San Luis Gonzaga.

This was our base, from which we made spins out into the Sea of Cortez in an inflated Zodiac boat to the Galapalos-like islands known as the Enchanted Islands.

We visited thousands of nesting pelicans, watched their velvety chicks, were surrounded by hundreds of barking sea lions, heard the eerie blow of a finback whale and watched his broad back slide across in front of us.

We left home with an edge of fear for everything from "banditos" to "turista" tummy, scorpions and rattlesnakes. We returned with deeply etched feelings for the mystery and majesty of Baja; memories of the best tomatillo fish sauce we had ever tasted; a wine lunch on a desert island; cactus campfires for lunch in the desert; margaritas at Catavina and grilled totuova freshly caught in the Sea of Cortez.

No banditos, no scorpions, no rattlesnakes and no "turista."

We went on one of the rare land trips in Baja. Most people fly in and out, or take a boat. Our guide was Piet Van De Mark, one of Baja's earliest expediton guides, of Baja Frontier Tours. He has been overseeing custom tours of Baja for 24 years -- since before the transpeninsular Mexico 1 was completed in 1973.

We spent four nights in sleeping bags and three nights in Mexican hotels to wash off the dust, gas up our truck, and let our bones shift back into the slots from which they had been jolted.

Van De Mark and his wife, Karen, are not only expedition leaders, passionate environmentalists and expert naturalists, but they also see to it that the food is both good and interesting. Piet is the premier chef and wine connoisseur. Karen is the sous chef and does the chopping, slicing, grating, desserts, and kitchen clean-up. But she let Piet whip the cream, which takes 7 minutes with a French whip.

Tailgate lunches were usually in the desert in the shade of a grotesquely twisted elephant tree or the shadow of monolithic granite boulders. From the truck would emerge fresh Mexican baguettes, smoked turkey, alfafla sprouts, avocados, all washed down with fruit juice or cool Mexican beer.

Never a fan of the desert, I was stunned by the surrealistic landscape that unfolded as we left the coastal plains of the Pacific and climbed into the high desert. Gone were all preconceived images of barrenness. There I caught my first glimpses of 80-foot cirio or "boojum" trees, 50-foot cardon cactus, and spiky, flame-tipped ocatillos, the most spectacular of the bizarre vegetation of Baja, much of which is found nowhere else in the world. Baja is a naturalist's dream, a setting that seems created by Stephen Spielberg with help from Salvador Dali and Lewis Carroll. The Baja high desert appears to be a garden of mammoth plants that were flipped over, the grotesque root systems left heaving in the air.

Our trip took us on stretches of the worst roads in Baja -- rocky roller-coaster roads used by the famous Baja 1,000-mile racers. Other stretches had not seen a road blade for 50 years and those that had were sometimes rougher. Even the highway travel was treacherous -- no shoulders, blind curves, and open cattle ranges where an occasional Mexican cowboy would wave a lariat at us as we passed his herd and pack mule.

Van de Mark remembers when the little ranches along the way were pit stops where people could get a meal, work on their cars, spend the night or band together with other drivers to repair the road so they could get through.

Those were the days, he says, when you'd had a good day if you made 20 miles, and if you met another car on the road the first thing you did was stop, build a fire, fix a pot of coffee and tell each other the news, the weather or the road conditions ahead.

Off the highway, we made 40 miles in 2 1/2 hours, passing only one truck and a Mad Max who roared past us in a cloud of white dust in a Volkswagen Baja buggy powered, we learned when we met up with him later, by a Porsche engine.

We pitched Edmund Hilary-designed tents just above the rocky tideline at Papa Fernandez' fishing camp on the Sea of Cortez where Van De Mark leases a palm-thatched casita. A bleached whale skull hangs above the door into the propane-powered kitchen and the screened dining room also houses the Zodiac engines and barrels of drinking water.

On Zodiac spins in the Sea of Cortez we tied up at Isla San Luis, uncorked the wine and dined in the silent splendor of a desert island -- just us and the seagulls nesting on speckled gray-green eggs in seaweed nests built in the warm volcanic sand.

Another day we lunched in the Zodiac with the sea churning around us as hundreds of barking sea lions slid from rocky ledges of their haven on Isla Coloradita and swarmed socially around our boat as we approached.

There's a pit privy on the rocky hillside at Fernandez's camp, and you get a pan of precious fresh water for washing. But there were 4-inch-thick foam rubber mattresses for our sleeping bags and the view through the screened tent flap was the beautiful blue day and the red basaltic mountains.

At night coyotes stalked silently by in front of the tent while we watched from sleeping bags as Halley's comet turned tail and headed fuzzily back into space.

If this sounds primitive, Van De Mark has had some of his hard-core Sierra Club clients complain that it was too comfortable to be true wilderness camping.

It is sheer luxury compared with the earlier days when they camped on the islands in the Sea of Cortez with the guano and flies and everything had to be transported across choppy water in the Zodiacs.

At camp we dined fashionably late, usually exhausted from a full day in the boat, snorkeling in the bay, beachcombing and exploring the tidepools, or fastened to binoculars to classify the latest blue-footed booby or orange-billed oystercatcher.

Appetizers were artichokes with mayonnaise and lime, or a pan of hot nachos, dripping with cheese and ready to be dipped in bowls of salsa and guacamole. Or, we might have an antipasta.

A Mexican quiche and salad with several wines was served one evening, a casserole with tamales hidden in a bright custard filled us another evening. And the stunning highlight was grilled totuaya, a rare specimen of the sea bass family.

In an area this remote with supermarkets 250 miles away, food is important and shared. After the totuova was filleted, the fish frame was carried to the Fernandez family for a fish stew.

In the Gulf of California the tide swings wildly. Tide charts are shown not just with times of high and low tides but with graphs to let you know whether you are in a week of big swings of perhaps 20 feet or just a mild swing of 5 or 6 feet. The disadvantage is that you don't go off and leave a boat on the shoreline or it may not be there when you come back.

Ah, but there is a real advantage to this. On a low low tide you can take an oyster knife, search the tideline for a cluster of oysters, take along the salsa bottle and a fresh cut lime to fix yourself the best breakfast in the world.

On our way home, for our final lunch in the desert near Catavina, we gathered chunks of dead cactus for a fire, cut hot dog sticks from a creosote bush and grilled split polish sausage, which we devoured with mustard and pepperoncini.

CHILAQUILES (TORTILLA HASH) (4 servings)

Camp breakfasts were beautiful with big platters of fresh fruit slices -- mango, papaya, fresh pineapple, Mexican bananas, strawberries and Mexican limes served with a fluffy cornbread and honey or Van De Mark's whole-wheat french toast and maple syrup. But at our hotel breakfasts we discovered chilaquiles, a peasant dish designed to use up stale tortillas (and anything else that needs eating). This is another dish that would make a splendid Sunday brunch item.

You could give it more color with bits of fresh tomato, or turn it into a luncheon dish with the addition of chopped cooked chicken.

6 corn tortillas

3 tablespoons salad oil

1/2 cup onion, diced

1/4 cup chopped canned California green chilies

1/2 teaspoon salt

6 eggs, beaten

1 cup shredded monterey jack cheese or medium sharp cheddar cheese

Salsa for serving

Cut tortillas into strips about 3/8-inch wide. Fry over medium heat in hot salad oil, stirring, until crisp. Add diced onion, chilies, salt and eggs and mix well until eggs are set. Sprinkle with cheese, run under broiler until cheese melts, about 1 minute. Top each serving with a dollop of red salsa.

PIET VAN DE MARK'S QUICHE ISLA SAN LUIS (6 to 8 servings)

All our superb meals cooked in the rustic kitchen of the base camp on Gonzaga Bay were the same ones that Piet Van De Mark does when camping in the desert or on the nearby islands using propane burners and a folding oven. In camp, he says you can save dishes by assembling ingredients in the pie shell, blending carefully so as not to break the baked crust. He rolls out ready-mix pastry with an empty wine bottle. A newer idea was the tortilla "petal" crust.

FOR THE CRUST:

Pastry shell for 9-inch pie, or, 6 or 7 corn tortillas*

Oil for pie plate

FOR THE FILLING:

2 ounces grated mozzarella cheese

4 ounces grated Swiss cheese

4 ounces grated mild cheddar cheese

4-ounce can diced green chilies, about 1/2 cup

3 cloves garlic, finely minced

1/4 chopped onion or fresh chives

1 teaspoon cilantro, finely chopped

5 large eggs, beaten

3/4 cup light cream

1/8 teaspoon dried oregano leaves

1/4 teaspoon dried basil

Salt to taste

Red salsa to taste

Bake pie shell at 375 degrees 5 minutes. Cool slightly. Scatter cheese in pastry shell (or tortillas shell), sprinkle with chilies, garlic, onion, cilantro. In a bowl combine eggs, cream, oregano, basil and salt. Pour over cheese mixture. Bake in a 475-degree oven for 10 minutes. Reduce heat to 325 degrees and continue baking 25 minutes or until filling is set.

Cool slightly before cutting into wedges. Serve with salsa and garnish with cilantro sprigs.

Van De Mark serves this with fresh vegetables, crusty garlic bread, Fetzer gewu rztraminer wine, and a Mexican Cointreau.

* To make tortilla petal crust: Using tongs, lay tortillas directly on flaming gas stove burners just until they begin to bubble, about 15 seconds, turn with tongs and heat other side. A few small scorched spots are acceptable and give it a smoky flavor. Line oiled pie plate allowing tortillas to overlap and extend about 1 inch above pie plate rim. If you have an electric burner, heat tortillas in a skillet. (Tortillas may be heated in oil to soften, but this just adds calories.)

HALIOTIS' PESCADO BLANCO WITH ESMERALD SALSA (Fish Fillet With Tomatillo Sauce) (4 servings)

"I know I'm going to like this trip," said one of the Baja expeditioners with a sigh after one bite of abalone at our first Mexican lunch at the Haliotis restaurant in Ensenada. Haliotis is the Latin name for abalone, but I was taken with the wonderfully fresh, moistly cooked halibut, which had a delicate tomatillo and cilantro sauce with just enough chilies to make it sing.

Fresh tomatillos vary widely in both sweetness and acidity. You will simply have to taste and adjust. If you like hotter sauces, add the additional chilies. Do not attempt to substitute green tomatoes for the tomatillos. They may look similar but the taste is completely different.

This sauce is delicious hot or cold and leftover sauce is wonderful with tortilla chips, grilled beef, cold shrimp or on Mexican omelets.

FOR THE FISH:

1 1/2 pounds fresh halibut or red snapper fillets

Salt to taste

1 garlic clove

Juice of 1 lime

2 tablespoons olive oil for cooking

FOR THE SAUCE:

3/4 pound fresh tomatillos (or 13-ounce can whole tomatillos**, drained)

2 tablespoons olive oil

3 tablespoons scallions, chopped tops included

2 to 4 serrano chilies*, stemmed and finely chopped

1 cup chicken broth

1/2 teaspoon sugar

1/2 teaspoon salt

1/2 cup cilantro leaves, loosely packed, finely chopped

1 tablespoon white wine (optional)

Cilantro sprigs for garnish

In a shallow glass bowl, place fish fillets and sprinkle with salt. Press garlic and rub into fish. Add lime juice and marinate at room temperature, covered at least an hour (preferably 2), turning fish occasionally.

Cook fresh tomatillos by removing papery husks and placing in a pan in enough simmering water to cover. Cover and cook gently 20 minutes or until tender. Drain.

To make sauce, heat olive oil in a heavy saucepan and saute' scallions and chilies until limp, about 1 minute; add chicken broth and tomatillos, sugar and salt. Cover and simmer over low heat about 5 minutes. Add cilantro, cook another minute. Taste and correct seasonings. If too sweet add the wine. Cool slightly, place in blender and blend only long enough to thoroughly mix.

Heat 2 tablespoons olive oil in a skillet with cover, add fish fillets, saute' until golden, turning once, about 4 or 5 minutes. Do not overcook. Serve with a dollop of tomatillo sauce and a sprig of cilantro. (If fillets look very neat, put sauce beneath them. If not, spoon a stripe of sauce on the fillet.)

* Serrano chilies are small, dark green and very hot. Wear plastic gloves when working with hot peppers. One rule of thumb for fresh peppers is that the smaller they are the hotter they are.

** Canned whole tomatillos can be found in Latin markets labeled Tomatillo Entero.

GRILLED TOTUOVA WITH "PABLO NEWMAN" MARINADE (6 servings)

You won't be able to buy totuova fish for this because it is off limits to sport fishermen and cannot be exported. We were the recipients of a 25-pounder caught in the nets of the local Mexican fishermen. It was a rare chance to taste this special fish, one of the wonders of the Sea of Cortez. Up to 300-pound specimens were caught back in the '50s on their migration north to lay their eggs in the Colorado River Delta. It was fished until nearly extinct but is making a comeback now with government protection.

The flesh was brilliantly white and the texture was smooth and soft but firm enough to hold together to be grilled to moist perfection.

Nevertheless, this is a simple method for preparing a firm-fleshed fish when camping or picnicing without a wide assorment of ingredients available.

2 1/4 pounds firm fish steaks, swordfish, grouper or shark, cut 1 inch thick

1/3 cup Paul Newman salad dressing

1/3 cup lime juice

Marinate fish steaks for 2 hours or more in salad dressing and lime juice. Grill over hot coals until fish is barely done. This should take no more than 7 to 10 minutes total cooking time.

ELOTES (Fresh Field Corn) AND GRILLED MEXICAN VEGETABLES

The elote stands we saw in Tijuana and Ensenada gave us an idea. These stands had steaming washtubs heated with wood fire and filled with ears of corn boiled just until tender. They are served with butter, a squeeze of Mexican lime and a splash of hot sauce. Sometimes the cooked corn is browned over charcoal.

It was such a good idea we tried the seasoning with charcoal grilled onions, zucchini and eggplant. Just slice onions crosswise about 3/4-inch thick. Zucchini and eggplant are sliced in 1/2-inch lengthwise slices. Marinate in olive oil spiked with lime juice and either hot sauce or taco sauce. Grill over charcoal about 3 minutes per side.

FLAN (8 servings)

Nearly every Mexican restaurant has its own version of flan, the Spanish custard that is a cousin to the cre me brule'e of the French. We did flan "tests" for dessert in every restaurant. Karen Van De Mark, who had been testing the length of Baja, awarded highest marks to the flan at El Presidente Hotel in La Paz and Malarrimo, the super seafood restaurant at Guerrero Negro.

2 tablespoons water

1 cup sugar

12-ounce can evaporated milk

1 cup whole milk

1 teaspoon vanilla

3 eggs, beaten

3 egg yolks

Add water to 1/2 cup sugar in a 8 or 9-inch skillet and bring mixture to a boil. (Use brush dipped in water to push down sugar crystals on side of pan.) Boil over high heat, without stirring, until it turns a rich amber color, about 1 minute. Now stir until it turns a golden caramel brown, about 1 minute. Remove from heat. Immediately pour into a 9-inch baking dish at least 3 inches deep (or, use 8 oiled custard cups.)

In a mixing bowl, beat together the remaining ingredients, including the remaining 1/2 cup sugar. Pour into sugared dish or cups. Place in a larger pan half filled with water. Cover with foil and bake at 350 degrees for 55 minutes or until custard is set in the middle.

Remove from oven, uncover, cool at room temperature 30 minutes, cover again, refrigerate until ready to serve. To unmold, run a knife around edge and invert over serving plate. Sauce will soften during refrigeration. This may be prepared two days in advance.