IN Spain, they are called tortillas. Italians refer to them as frittatas. In the Mideast, they are kukus.

In English, we call them a bargain, these deep open-face omelets that turn leftovers quickly into luncheon or supper. Egg sales at Easter are as abundant as hot dogs at RFK. With their prices low, eggs appear as frequently on tables as they do in Easter baskets.

Eggs are often avoided because of their high cholesterol content. While they are one source of concentrated dietary cholesterol, they are not necessarily the culprit in high blood cholesterol. "It's more important to look at sources of saturated fat," says Bonnie Liebman, nutritionist at the Center for Science in the Public Interest. While she agrees with the American Heart Association limit of three eggs a week, she cautions people not to rely on an eggless diet to lower blood cholesterol. Rather, people should take a look at the "meat, cheese, whole milk, butter and pastry" that they are eating.

While the confusion about cholesterol and egg yolks persists, their attractive price and high holiday visibility make eggs an attractive choice for spring meals. Some stores are selling eggs more than 30 cents a dozen below last April's price. As a result, says Barbara Beizer, consumer adviser for Safeway, egg sales have doubled. Last year Safeway's 155-store division that includes the Washington area sold 262,018 dozen eggs in the week before Easter; this year sales reached 412,215 dozen.

Poached, fried and soft-boiled eggs might remain relegated to the breakfast tables of energetic cooks. As omelets, however, eggs are destined for more.

In any language, this express-lane egg dish suits hors d'oeuvre trays and dinner buffets. It receives graciously all manner of accouterments--spicy Italian sausage, green peppers, grated cheese and mushrooms appear as easily here as they do on pizza. And because the dish is only one step away from scrambled eggs--there's no fancy flipping or folding--nothing can foul up.

In other countries the dish is as popular served at room temperature as it is hot. Here people prefer their eggs slid right from skillet to serving platter. The dish becomes dinner after one quick trip through the express lane, provided you already have flour, sugar, salt, pepper and butter, vegetable oil or olive oil on hand. EXPRESS LANE LIST: Sweet peppers, eggplant, eggs, walnuts, scallions, snow peas, cherry tomatoes. EGGPLANT KUKU (4 servings) 2 large red or green bell peppers 1 medium eggplant 10 eggs 3 tablespoons chopped walnuts, toasted 3 tablespoons chopped scallions (reserve green tops) Olive oil Salt and pepper to taste

Broil the peppers until black on all sides. Set aside. Peel the eggplant and slice lengthwise about 1/2-inch thick. Place slices on a flat baking sheet and broil on both sides until they begin to brown. They will shrink considerably and brown only lightly. When the peppers are cool enough to handle, peel, seed and sliver them in 1/4-inch strips. Beat eggs and add peppers, walnuts and chopped scallions. Brush the bottom and sides of a very large skillet with a generous coating of olive oil. Line skillet with eggplant slices and sprinkle with salt and pepper. Pour egg mixture over the top and cook over very low heat until all but the surface is gently set--this may take 15 or 20 minutes. Place the skillet under a preheated broiler to finish the top--about 30 seconds. Flip the kuku onto a large serving plate and cut into quarters.

Note: Substitute any vegetables (leftover or fresh) for the peppers and eggplant. For instance, you can mix chopped, cooked potatoes into the eggs and pour them over cooked spinach. Nuts give a pleasant crunch and richness to the dish, but may be omitted. SPRING MEDLEY (4 servings) 1/2 pound fresh snow peas 1 pint cherry tomatoes 2 tablespoons olive oil 2 to 4 tablespoons scallion tops Salt and pepper to taste

Wash and trim peas and cherry tomatoes. Heat oil in a large skillet. Add peas, tomatoes and chopped scallion tops. Shake pan constantly until vegetables have heated through, about 4 minutes. Season to taste with salt and pepper.