Breakfast : 8 Places Off the Beaten-Egg Track : Ethnic fare: Breakfast is many things to many peoples, as L.A.’s restaurants prove. A sampling from the variety available to a.m. adventurers. : Mexican

The staff of life seldom goes to waste. In the United States, leftover bread might reappear on the breakfast table as French toast. In Mexico, leftover tortillas turn up in chilaquiles , a dish of tortilla chips moistened with sauce and garnished with meat, cheese or whatever is on hand.

Although you can eat chilaquiles at any time, the dish comes into its own at breakfast. You’ll find it in morning buffets at tourist resorts in Mexico as well as in cafes appealing to locals.

In Montebello, chilaquiles star in the campesino breakfast at El Porton, a restaurant that offers the sort of food you would find in Mexico rather than Americanized adaptations. This restaurant is the first American outlet of CIFRA, which has 80 restaurants in Mexico, including 14 El Portons. The Montebello branch recreates their menus and atmosphere, as will another set to open in Westwood in early 1991.

El Porton serves a sturdy plateful of chilaquiles . The tortilla chips are mixed with tomato sauce spiked with enough serrano chile to wake you up. Shredded chicken goes on top, then sour cream, diced onion and a sprinkling of the Mexican cheese, queso fresco.

Breakfast starts with fresh fruit or juice, and, by the way, the orange juice is really freshly squeezed. The coffee is the wonderful cafe de olla of Mexico, spiced with cinnamon and sweetened authentically with cones of rich dark sugar, called piloncillo. There is frothy Mexican-style hot chocolate too, scented with cinnamon like the coffee. And if you have an appetite for more, try a churro, the long-ridged cruller that is a classic companion to hot chocolate.

El Porton, 1105 W. Whittier Blvd., Montebello; (213) 888-8879 or (213) 888-2953. Open Sunday through Thursday from 7 a.m. to 10 p.m. Friday and Saturday from 7 a.m. to 2 a.m.

EL PORTON’S CHILAQUILES

16 corn tortillas

Oil for deep frying

Ranchera Sauce

1 cup shredded cooked chicken

1/2 cup diced white onion

1/2 to 3/4 cup crumbled queso fresco

3/4 cup sour cream

Cut tortillas into 8 wedges. Heat oil in deep, medium skillet. Fry tortilla wedges in batches until browned and crisp. Drain on paper towels.

Combine 1 cup Ranchera Sauce and chicken in saucepan and heat. Heat remaining sauce in large skillet or Dutch oven. Add tortilla chips and stir gently 3 minutes, until moistened.

Divide tortillas among 4 serving plates. Top each serving with some chicken and sauce, then onion, crumbled cheese and sour cream. Makes 4 large servings.

Ranchera Sauce

8 medium tomatoes, coarsely chopped

1 onion

1 tablespoon chopped garlic

6 serrano chiles, minced

Salt

Combine tomatoes, onion and garlic in blender and blend until pureed. Pour into skillet and boil 20 minutes. Season to taste with salt. Skim off foam. Makes 5 1/2 cups.