The small Balkan countries of southeastern Europe have long been known for their culinary specialties prepared with yogurt. In these areas yogurt is a staple food that is still traditionally made daily in the homes, eaten regularly at meals and between them, and used creatively in cooking.

Some of the best and most interesting yogurt dishes are soups and salads which have interchangeable roles on the menu and are excellent summer fare.

Yogurt was first prepared as a soup in the Balkans in ancient times when such flavorings as garlic, onions and herbs were mixed with it. During the summer it was eaten cold and in winter months in was served hot.

Today there are excellent clear soups made with broths and yogurt. The Bulgarians lace a favorful meatball-rice soup with yogurt and the Yugoslavs add yogurt to their hearty lamb-vegetable corbas. In Albania, yogurt is commonly used to make vegetable soups flavored with herbs, especially mint. Yogurt also adds flavor and nourishment to basic soups made with noodles, dried beans, rice and such vegetables as onions, tomatoes and cabbage.

Balkan salads, eaten with other appetizers before the main meal, or as an accompaniment to poultry and meat, have a particular importance as they add a cooling and refreshing contrast to the heavily spiced foods that follow.

Typical salds are those made with yogurt and chopped raw vegetables - onions, radishes, sweet and hot peppers, cucumbers, tomatoes - and seasonings. But yogurt can also be added to cooked greens, carrots, eggplant, potatoes, beets and squash, and served cold.

Onlyplain yogurt should be used to make the following recipes. It can be purchased or prepared easily and inexpensively in the home, with or without special equipment. The simplest way is to innoculate heated and cooled milk (fresh whole or skimmed, canned or powdered) with a small amount of a prepared yogurt or a powdered culture and then to keep it warm during the incubation period. A good warm place is over the pilot light of a gas stove. Electric yogurt-makers may be purchased in most stores selling kitchen equipment.

BULGARIAN TARATOR

(Serves 4 to 6)

This popular cool soup or appetizer may also be made without walnuts and flavored with fresh mint or parsley and lemon juice. One interesting variation includes yellow or golden raisins. 2 medium cucumber, peeled, seeded and diced Salt 4 cups plain yogurt 1/2 cup finely chopped walnuts 2 or 3 garlic cloves, crushed or minced 2 tablespoons olive oil 1 tablespoon red wine vinegar 2 tablespoons chopped fresh dill White pepper to taste

Put diced cucumber in a colander or bowl and sprinkle with salt. Leave to drain for 30 minutes. Pour off liquid. Mix with remaining ingredients in a large bowl and chill at least 1 hjour to blend flavors. Serve in individual soup bowls or dishes with one or two ice cubes in each, if desired.

BEET-YOGURT SALAD

(Serves 6 to 8) 3/4 cup plain yogurt 1 tablespoon vinegar 2 tablespoons chopped fresh dill or parsley Salt, pepper to taste 2 cans (1 pound each) julienne beets

In a bowl combine yogurt, vinegar, dill or parsley and season with salt and pepper. Blend well and chill. Drain beets and chill. To serve, spoon yogurt mixture over beets.

EGGPLANT-YOGURT SALAD

(Serves 4 to 6) 1 eggplant, about 1 1/4 pounds, washed 1/2 onion, peeled and minced 2 garlic cloves, crushed or minced 2 tablespoons olive oil 1 tablespoon fresh lemon juice 1/2 cup plain yogurt Salt, pepper to taste 3 tablespoons chopped fresh dill or parsley Paprika or cayenne

Prick eggplant in several places and put on a small baking sheet or pie pan. Put under a heated broiler and cook, turning several times, until the skin becomes charcoal black on all sides, about 20 minutes. Peel off skins while still hot and put pulp in a bowl. Mash thoroughly with a wooden spoon and pour off any liquid. Add remaining ingredients, except paprika, one by one and beat after each addition with a wooden spoon. Chill. Serve on a plate garnished with parprika.

YOGURT-CHICKEN SOUP

(Serves 6 to 8)

6 cups chicken broth Salt, pepper to taste 2 cups plain yogurt 1 tablespoon flour

2 egg yolks, well beaten 2 tablespoons butter or margarine 2 tablespoons chopped fresh mint, dill or parsley

Bring broth to a boil in saucepan. Season with salt and pepper. Lower heat to medium. Combine yogurt, flour and beaten egg yolks in a small bowl. Stir in some of hot broth and mix well. Return to broth. Cook over low heat, stirring, 1 or 2 minutes. Add butter and mint and serve at once. Do not reheat.