Most working cooks have a small reservoir of reliable recipes that are easy to execute, those on which they often rely for family meals in rushed circumstances. Meat loaf and spaghetti sauce are such recipes--holdovers from the '50s. Sometimes there's a specialty soup or chicken-breast-something.

Egg foo yung should take a steadfast position in the usually small but cherished repertoire. The cook combines thoughtless preparation with popular Chinese ingredients to produce a new verse for the American scrambled eggs theme. Unlike many Chinese-inspired dishes, this one takes a minimum of cutting and slicing--the scallions require chopping but the bean sprouts need only rinsing and drying.

Not only is it quick and easy to prepare, but no major dinner decisions have to be made until you get to the grocery. While you're packing your fresh bean sprouts and picking up your eggs, you can mull over the basis of the main course. You can be ambivalent and change your mind at the last minute if you had all intentions of eating chicken tonight but it was such a bad day you think you might splurge on shrimp. Pork chops on sale might entice the economy-conscious cook--sliver one or two and add them to the eggs--while opening a can of crab meat may be a monumental effort for another. The cook with a refrigerator full of leftovers may decide on short-order foo yung, relying on pieces of roast or ham that are waiting at home.

In any case, dinner is easily prepared with a quick trip through the express lane of a supermarket, provided you have oil, salt and pepper in the kitchen at home.

EXPRESS LANE LIST: eggs, scallions, bean sprouts, shrimp, soy sauce, rice, peas, mushrooms. EGG FOO YUNG (4 servings) 8 eggs 1/4 to 1/2 pound uncooked shrimp 1 bunch scallions, chopped, including green tops 1 1/2 cups bean sprouts, washed and drained 1 teaspoon soy sauce Freshly ground pepper to taste Vegetable oil

Beat the eggs. Peel and chop the shrimp. Stir in scallions, sprouts, soy sauce and a little pepper. Heat a few tablespoons of oil in the bottom of a 10-inch skillet. Pour in the egg mixture and using a spatula, pull the vegetables in toward the center, allowing the liquid egg to pour down to the hot edges of the pan. Do this all around the egg mixture, allowing the liquid egg to fall down to the edges to set as you draw the cooked egg mixture toward the center. Flip onto a warm serving platter and slide back into skillet, uncooked side down. Cook about 2 minutes over medium-low heat. Slide back onto the platter and slice in triangles. Serve with hot fluffy rice and pass extra soy sauce, if desired. PEAS AND MUSHROOMS (4 servings) 4 ounces fresh mushrooms 2 tablespoons butter 2 cups peas

Wash mushrooms, dry well and slice. Melt butter in a large skillet. Add mushrooms and cook over medium heat for about 5 minutes. Add peas (along with a little water, if they are fresh), cover and cook until tender (this should only take a few minutes)