CINCO de Mayo -- The fifth of May--is a national holiday in Mexico, and in the American Southwest an occasion to celebrate Mexican cultural heritage with springtime street festivals.

The Mexican national holiday marks the beginning of the end for French control of Mexico in 1862, when Mexican loyalists led by Benito Juarez turned the tide of revolution by winning a battle in Puebla, southeast of Mexico City.

Although this holiday has no particular food tradition, it seems a logical time to further the understanding of Mexican cultural heritage--for those less familiar with it--through cuisine.

A menu including corn and chilies launches just such a cultural journey. As corn is the staff of Mexican life, chilies are its compass--the selection and mixture of the dozens of chilies determines the nature of the sauce--from dark rich adobo sauce with ancho chilies to the lighter, snappier salsa cruda of fresh tomatoes and minced jalapenos.

The following dish combines both corn and chilies in what might be considered leftovers in Mexico--a dish often made with stale tortillas and ubiquitous hot sauce. It is hearty and filling and needs cold, juicy fruit as an accompaniment. Peeled, sliced oranges or chilled melon wedges are perfect.

The entire meal is possible with a trip through the express lane of the supermarket, provided you have salt, pepper and vegetable oil at home. If your express lane allows another item, pick up a jalapeno or serrano pepper to give the dish some kick.

EXPRESS LANE LIST: tomatoes, onions, oregano, green chilies, tortillas, cheese, chicken, oranges or honeydew melon and optional jalapeno or serrano chili pepper. CHILAQUILES (4 to 6 servings) 2 medium onions 35 ounces canned plum tomatoes 1 teaspoon oregano 1/2 teaspoon freshly ground pepper 1/2 teaspoon salt, or to taste 1 or 2 serrano chilies, minced (optional) 3 chicken breasts 8 mild green chili peppers or 2 4-ounce cans of mild green chilies 18 corn tortillas 8 ounces monterey jack cheese

Quarter the onions and drop into a blender container. Add half the tomatoes and the oregano. Blend until smooth. Pour into a large skillet and place over medium heat. Blend remaining tomatoes and add to skillet with salt and pepper and optional hot chilies. Place chicken breasts in simmering water to cover and cook 15 minutes. Remove and set aside. While the chicken breasts are cooking, broil green chilies very close to the broiler element until they are charred on all sides. Remove, and when they are cool enough to handle, peel and seed them. Cut into 1/2-inch-wide strips and set aside. Slice tortillas into 1-inch-wide strips. Grate cheese. Remove skin from chicken and discard. Remove the meat from bones, peeling it down in strips along the grain of the meat. Place 1/2 cup tomato sauce in the bottom of a deep 2-quart greased baking dish. Layer with 1/3 of the tortilla strips, 1/3 of the green chili strips, 1/3 of the chicken and 1/3 of the cheese. Cover with a cup of sauce. Repeat layering twice, topping the mixture with remaining tomato sauce (about 1/2 cup). Bake at 350 degrees for 30 minutes. Remove and let stand 10 minutes before serving. Serve with cold fruit such as sliced oranges or melon.