"Vamos de tapas." "Let's go for tapas," is the cry that resounds throughout Spain's capital city around noon every day and then again between 6 and 9 at night.

Tapas are those little snacks served at every corner tasca (bar) in every large city throughout Spain. More often than not, a tasca will specialize in regional dishes of the owner's home province. So, in a melting-pot city like Madrid, simply by moving from one tasca to another, you can start with Galician-style octopus, progress to Andalusian pescaditos (little fish), and then finish off with a slice of manchego cheese from Don Quixote's part of the world--La Mancha.

They also stave off the suffering of strangers to Spain's dining traditions. As travelers to Spain quickly learn, no respectable restaurant admits patrons before two o'clock for lunch or nine for dinner. In fact, even if you've cajoled your palate into waiting for the restaurant's doors to swing open, you'll find yourself utterly alone in the dining room if you arrive within the first hour. Three o'clock is preferred for the "midday" meal in Spain, and the ideal dinner hour falls between 10 and 11. A bit late by American standards, to put it mildly.

Tapas to the rescue. Could there be a more pleasant way for visitors--and for the Spanish, themselves--to contend with those long, stomach-growling hours between meals?

But legend has it that the origin of eating tapas had more to do with thirst than with hunger. Back in the 13th century, it is said, stagecoach drivers were in the habit of getting drunk on the job. It seems they liked to break up long journeys by stopping at roadside taverns for long, comforting quaffs of local wine.

To assure disgruntled passengers that they would arrive safely at their destinations, a law was passed prohibiting bar owners from selling a drink without covering the mug with a little plate of bread, ham or some other solid food that would counteract drunkenness. The Spanish word tapas, meaning cover, originally referred to the plate covering the mug, but eventually came to be used to refer to the snacks themselves.

From these humble beginnings, the Spanish have evolved such a mind-boggling array of tapas that for many it's not the drink, but the food, that is the tasca's greatest allure.

There are certain staple items most tascas seem to have. Torta espanola, the mellow potato omelet served in wedges, will almost always be available, as will seasoned olives and some type of cured ham. Marinated mussels, fried squid rings and potato croquettes are also seen everywhere..

Bread served at the tascas is the French-style long loaf, and a generous length of six to eight inches cut into 3 to 4 slices will always be set on the counter to accompany your racion, as each small portion is called. A racion usually sells for between $2 and $3, but nobody is likely to stop at one.

Each tasca offers a wide range of spirits, beer, tinto (red wine), and blanco (white wine). Sold by the glass, the wine in most Madrid tascas is from nearby Valdepenas. It's a young wine, light, undemanding and easy to drink--the ideal accompaniment to a tapa redolent of garlic.

Despite certain similarities, each tasca is an adventure unto itself, with its own special atmosphere and clientele. One will specialize in grilled kidneys or brains, another in skewered green peppers and sausages, yet another in shrimps saute'ed in garlic butter or grilled. (You can always tell when a tasca is famous for shrimp because the floor will be carpeted with the peelings.)

Surely the most interesting tascas are those that have a strong flavor of their owner's birthplace. If you visit an Asturian tasca, for example, you'll find that region's famous cider poured in an arc over the barman's head--as if by magnetic force--into your glass.

A Galician tasca, on the other hand, will display enormous tentacles of octopus and those ugly but delicious black and white barnacles called percebes. Seafood will be the specialty and it will all be fresh.

Enter a Basque pub, though, and you will find plates of flaked, dried codfish mixed with garlic mayonnaise. And the men at the counter, their round faces topped off with berets, will end their snack with a hearty gulp of pacharan, the sweet red-currant liqueur that is part of their gastronomic heritage.

Tapas are ideal for serving at a cocktail party. Here are some simple recipes that will comfortably serve eight as pre-dinner snacks.

For drinks, try a chilled, dry fino sherry or a hearty red or white rioja. And don't spare the toothpicks and napkins. TORTILLA ESPANOLA (Potato Cake) (4 to 6 appetizer servings)

This dish is loved throughout Spain and is available by the wedge in most tascas. For a cocktail party, serve it at room temperature, cut into bite-sized squares and secured with toothpicks. 1/2 cup olive oil 1 1/2 pounds potatoes, peeled and thinly sliced 1 medium onion, peeled and thinly sliced 6 extra-large eggs, lightly beaten 1/2 teaspoon salt, or to taste

In a 9-inch, straight-sided skillet, heat the oil. Reduce the flame to low and add the potato and onion slices, turning all the while to coat them evenly with oil. Cook over low heat, turning frequently, until the potatoes can be easily pierced with a fork, about 30 minutes. (Take care that the potatoes do not brown.) Remove the potatoes and onions and drain them on paper towels.

Place the potatoes and onions in a large bowl. Mix the eggs with the salt and pour over the potatoes. Let stand for 10 minutes at room temperature.

Meanwhile, pour off and reserve any oil from the skillet in excess of about 1 tablespoon. Scrape off and disregard any brown bits stuck to the bottom of the pan. Heat the remaining oil and pour in the potato-egg mixture, pressing with a spatula to form a firm cake. Cook over medium heat until the bottom is browned, about 4 minutes. Loosen the sides and bottom of the "cake" with the spatula and invert the "cake" onto a plate. Spread an additional tablespoon of oil onto the bottom of the skillet and cook the other side of the "cake" until browned. Slide the finished "cake" onto a serving platter and store at room temperature until needed. CHAMPINONES RELLENOS (Stuffed Mushrooms) (4 to 6 appetizer servings)

These may be prepared a few hours in advance and then baked just before needed. 16 very large mushrooms (about 18 ounces) 2 tablespoons olive oil 5 teaspoons finely minced garlic 4 ounces cured ham, very finely minced 1/4 cup finely minced parsley

Wipe the mushrooms with a damp cloth and pry out the stems with your fingers or a knife. Place the mushroom caps, hollow side up, in shallow baking dishes. Finely mince the stems.

In a small saucepan, heat the oil. Fry the garlic for about 30 seconds, stirring constantly. Add the minced mushrooms stems, ham and parsley and cook over medium heat for two minutes. Stuff the mushrooms with this mixture.

Just before serving, bake the stuffed mushrooms in a 350-degree oven until cooked throughout, about 10 minutes. CALAMARES FRITOS (Fried Squid) (4 to 6 appetizer servings)

A very popular tapa, the squid should be fried just before it is served. Don't skimp on the lemon. 1 pound cleaned squid (preferably small squid which are the most tender) 1/4 cup flour Vegetable oil for frying 2 large eggs, lightly beaten Salt to taste 2 to 3 lemons, cut into wedges

Cut the squid into rings about 3/8-inch wide. Cut the tentacles, if necessary, into bite-sized portions. Toss the squid in flour to coat.

In a skillet, heat enough oil to measure about 1 1/2 inches deep. When the oil just begins to smoke, lower the flame slightly, dip a few pieces of floured squid into the egg and gently set them into the oil. Turn after a minute or two, and when both sides are golden, remove the squid immediately to drain on paper towels. (The squid should cook no longer than about 3 minutes or they will become very rubbery.) Continue cooking the squid in batches.

Set the fried squid on a platter. Dust liberally with salt, and squeeze some of the lemon on top. Garnish the platter with additional lemon wedges. (Fried squid is traditionally eaten with the fingers.) ACEITUNAS ALINADAS (Marinated Olives) (4 to 6 appetizer servings)

It is quite a simple matter to turn rather undistinguished black olives into "you-can't-stop-eating-them" snacks. Just be sure to prepare them a day in advance. 1/2 pound oil-cured small black olives 2 scallions, finely minced 2 large cloves garlic, peeled and crushed 1/4 cup red wine vinegar 1/4 cup Spanish olive oil 1/2 teaspoon paprika

Combine all of the ingredients in a jar. Secure the lid and shake well. Let stand at room temperature, shaking occasionally, for 24 hours. Serve in a small bowl.

Note: The marinade can be re-used. GAMBAS AL AJILLO (Garlic Shrimp) (4 to 6 appetizer servings)

In a tasca that specializes in gambas, individual portions of this dish will be prepared in a small earthenware casserole as you wait. The bread served on the side is traditionally dipped into the sauce after the shrimp are gone.

3 tablespoons butter 5 tablespoons olive oil 1 1/2 teaspoons finely minced garlic Generous pinch crushed red pepper flakes 1/2 teaspoon paprika 1 pound small shrimp, shelled and cleaned 2 tablespoons finely minced parsley 3 tablespoons lemon juice Salt to taste

In a large skillet or heatproof earthenware casserole, heat the butter and oil. Fry the garlic, red pepper and paprika about 10 seconds, stirring constantly. Add the shrimp and cook over medium-high heat until they turn pink, stirring constantly, about 3 minutes. Stir in the parsley, lemon juice and salt and serve immediately with toothpicks on the side.