Cooks in the Middle East and around the Mediterranean have long recognized that a soup based on cucumbers is one of the most refreshing appetizers for a hot summer day. Our ancestors in the Holy Land had plenty of experience preparing cucumbers, which have been known in our area since biblical times. In the Torah they were mentioned as a food missed by the Hebrews during their wanderings in the Sinai (Numbers 11:5; although the word used was kishu, experts have determined that these were cucumbers). Spanish gazpacho, made by blending cucumbers with tomatoes, olive oil, vinegar and bread, may be the most celebrated cucumber-based soup, but on the eastern side of the Mediterranean the favorite cold cucumber soup is much easier to prepare. To make it, most people simply stir cut cucumbers with yogurt and a few seasonings to get soups that are both creamy and cool. In these cucumber-yogurt preparations, the line between soup, salad, sauce and dip often blurs, so that the famous Turkish cacik and the Greek tzatziki might be described as any one of these. Basically, the ratio of cucumbers to yogurt determines whether the result is a salad or a soup. Benny Saida, author of Food from the Balkans (in Hebrew), makes cucumber-yogurt salad with six or seven thin-sliced cucumbers for two 170-gr. containers of yogurt, along with plenty of garlic, fresh mint and a little salt, sugar, vinegar and olive oil. For cucumber-yogurt soup, he combines diced cucumbers with three times as much yogurt as in the salad, and mentions that sheep's milk yogurt gives the best result. He flavors the soup with fresh dill instead of mint, garnishes it with chopped walnuts and suggests serving it with fresh bread or a Balkan cheese pastry (such as burekas). I think this makes a light and delightful summer supper. Instead of adding sugar, Madhur Jaffrey, author of World of the East Vegetarian Cooking, gives her soup a touch of sweetness by mixing the yogurt with milk or heavy cream. Neset Eren, who wrote The Art of Turkish Cooking, uses grated cucumber for a finer texture and seasons her soup with garlic, dill, mint, olive oil and vinegar. In Uzbekistan, wrote Lynn Visson in The Art of Uzbek Cooking, people like diced red and white radishes in their cold cucumber soup, along with a mixture of yogurt, buttermilk and sour cream and plenty of herbs, green onions, parsley, dill and coriander. Very crisp thin flatbread or whole-wheat crackers are the recommended accompaniment. Iranians have a more elaborate take on the cucumber-yogurt combo. Najmieh Batmanglij, author of New Food for Life, puts raisins in her soup of cucumbers, yogurt, sour cream, garlic, green onions, mint, dill and chopped walnuts. To enhance the cooling effect, she adds ice water, ice cubes and a garnish of chopped mint and rose petals. The rationale in creating this and other recipes goes beyond pleasing the palate, according to Margaret Shaida, author of The Legendary Cuisine of Persia. Foods are combined according to the concept of "hot and cold" that most people in Iran still adhere to today. Hot tempered children are given "cold" foods to calm them down, while docile ones get "hot" food to pep them up. Batmanglij also noted that recipes should combine hot and cold elements. The cucumbers and yogurt, which are "cold," are balanced with "hot" elements: raisins, walnuts, dill, mint, garlic, salt and pepper. This is not always consistent, however. Shaida explained that yogurt "is never mixed with summer fruits as it is in the West, for such mixing would result in a clash of the humors," since most soft fruits are considered "hot" while yogurt is "cold." Arto der Haroutunian, author of A Turkish Cookbook, feels that freshly made yogurt from goat, sheep or cow's milk is perhaps the most popular ingredient in his country. It is paired with a variety of foods. In one recipe he matches yogurt with diced grilled hot green peppers instead of cucumbers, as well as salt, garlic and parsley. A sweet version features carrots instead of cucumbers, as well as raisins, pomegranate seeds and mint. Eren makes a quick tomato yogurt soup by blending yogurt with tomato juice, olive oil, lemon juice, vinegar and curry powder. Romanians and Bulgarians make cool but filling yogurt soups by adding cooked root vegetables, according to Vladimir Mirodan, who wrote The Balkan Cookbook. For cold potato soup, they cook potatoes, carrots, celery, parsnips and parsley root, then finish the soup with buttermilk or yogurt and dill. Sometimes the potatoes are omitted, and the other cooked root vegetables are combined with diced cucumbers, green onions and dill. For a substantial soup from the Caucasus, Jaffrey adds cooked barley, sauteed onions and mint to yogurt. Chickpeas, cooked wheat berries and fresh mint appear in her Turkish/Armenian yogurt soup. Such soups are not only refreshing, they are satisfying enough to make an appealing one-dish supper, perfect for summer. COLD CUCUMBER TOMATO SOUP WITH YOGURT AND HERBS This appetizer is ideal when the weather is really hot. Garlic gives the soup a subtle kick that is balanced by the fresh flavor of the herbs. Use any yogurt you like; even nonfat yogurt gives good results. 1 garlic clove 1â„2 tsp. salt, or to taste 6 cups plain yogurt pinch of cayenne pepper 225 gr. small, good quality cucumbers 225 gr. ripe tomatoes 1 Tbsp. chopped fresh dill or mint 2 Tbsp. minced parsley 2 Tbsp. chopped chives Press garlic through a garlic press or mince it very fine. Mash garlic with salt in a large bowl, using back of a spoon. Add yogurt and cayenne pepper. Stir to blend thoroughly. Peel cucumbers if you like. Halve them lengthwise. Dice them small or grate them and add to yogurt mixture. Dice tomatoes small. Reserve about 1â„3 cup for garnish; add remaining diced tomatoes to soup. Fold vegetables gently into yogurt. Taste and adjust seasoning. Refrigerate at least 15 minutes or up to six hours before serving. A short time before serving, stir in dill, parsley and half the chives. Serve soup garnished with reserved diced tomato and remaining chives. Makes 6 servings. Faye Levy is the author of Feast from the Mideast.