The long vine of the cucumber has trailed across continents and over oceans for 4,000 years and makes its appearance in most fine cuisines of world.

Charlemagne was planting cucumbers in France in the 8 century but they'd already come a long way by then. It's a matter of record that cucumbers were around in Old Testament days and though it's not commonly known whether the Emperor Tiberius was fat or thin. It is known that the emperor gorged himself daily on the stubby gree gourds.

It is said that the English began growing them in the 13th century, although others say that the cucumber arrived in Britain by way of Egypt only at the end of the 16 century. In any event, by 1861 Mrs. Beeton included 12 recipes for cucumbers, only one of them pickled, in her encyclopedic "Book of Household Management." She felt forced to warn, however, that " . . . generally speaking, delicate stomachs should avoid this plant, for it is cold and indigestible." She included, too, the bit of geographic lore that " . . . in China, Cashmere and Persia they are cultivated on the lakes of the floating collections of weeds common to these localities."

In their long life cucumber's have created for themselves a mixed bag of reviews. They've been called everything from Mrs. Beeton's "indigestible" to "poisonous." But no one would hesitate to call them "simming." Ninety-six percent water, the average cucumber at its fattest cannot cram more than 25 calories into its whole green length.

There are certain partners with which cucumbers are at their best. They've lived in connubial culinary bliss with yogurt (in the Middle East) and sour cream (in Russia, where cucumbers grow abundantly). As the Chinese discovered, the cucumber's best cooking is done in a flavorful chicken broth, and they're happy as clam with crab - and indeed with almost any seafood or fish.

In addition to cucumbers, many of the ingredients in the recipes that follow are what diets are made of. PERSIAN CUCUMBER SOUP (4 to 6 servings) 3 cups yogurt 1 cup water 1 large cucumber 2 tablespoons finely minced green onion tops 1/4 teaspoon salt 2 dashes hot pepper sauce Fresh mint, chopped Raisins

With an eggbaater, blend yogurt until smooth. Gradually blend in cold water. Peel cucumber, shred or grate it as fine as possible (most food processors are adequate for this fine grating); do not drain. Add cucumber and its liquid, with the onions, salt and hot pepper sauce to the yogurt mixture. Chill ice-cold.

Before serving, sprinkle with chopped mint if you have it; substitute a few minced greed onion tops if you don't. Pass a small bowl of dark raisins for each person to scatter in at will. It's a remarkably good contrast.

Note: This makes a very thick "soup", almost solid. Blend in more cold water if a thinner soup is preferred. It is even better served the day after it's made. RUSSIAN CUCUMBERS AND RADISHES (6 to 8 servings) 2 to 3 cucumbers, sliced (about 3 cups) 2 cups sliced radishes 6 green onions, minced (1/2 cup) 1 teaspoon salt 1 teaspoon sugar 1 cup sour cream

Slice radishes very thin.Slice peeled cucumbers a bit thicker. Sprinkle lightly with salt and refrigerate for 1/2 hour. Mix onions and radishes and refrigerate. Stir 1 teaspoon salt and sugar throughly into sour cream; refrigerate.

Holding a plate over sliced cucumbers in bowl, drain cucumbers throughly. At this point, leave all ingredients refrigerated until just ready to serve; they should be chilled at least an hour, preferably more. At serving time, drain cucumbers again, and combine them with radish mixture and sour cream, turning carefully to coat each slice.

It may be used as a relish with a meat course, or ungarnished on individual plates as a first course. You may sterve it on lettuce leaves, Russians wouldn't. There is a built-in bonus. Put this whole amount, or any left over, into a blender or food processor and liquify to create a good cold soup. CUCUMBER FLORIDA KEYS (6 servings) 3 large cucumbers 3 medium tomatoes 1/2 cup chopped onion 1 teaspoon salt 10 to 12 grinds black pepper 3 slices bacon, diced 1/2 cup fresh bread crumbes browned in butter 1 tablespoon butter

Halve cucumbers lengthwise withoug peeling them. Leaving cucumber meat intact, scoop out seeds by running tip of spoon down cucumber's length. With tip of sharp knife cut out cucumber meat to within 1/4 to 1/2 inch of skin, and dice meat. Core unpeeled tomatoes and chop finely.Combine cucumber dice, tomatoes, onions and seasoning. Fry bacon very slowly in a skillet; do not fry chisp. When bacon is just becoming translucent, add vegetable mixture (pour off a part of the bacon fat if it seems too much) and saute 2 to 3 minutes, stirring gently. Remove from heat and stir in all but 3 or 4 tablespoons bread crumbs. In a skillet of boiling water to cover, scald cucumber halves 5 minutes, drain.

Heat over to 375 degrees. Fill cucumber halves with vegetable mixture and place in a shallow greased baking pan or over-to-table gratin dish. Sprinkle cucumbers with remaining bread crumbs, dot with butter. Bake in oven 30 to 45 minutes, testing largest cucumber skin for tenderness. Place under broiler last few minutes of cooking time, watching carefully. For a meatless main course, double recipe. Serve hot, or cook a day ahead and serve cold. COOL COOKED CUCUMBERS (4 to 8 servings)

This manner of preparing cucumbers in a slow-cooker leaves a summer kitchen cool and provides an unusual vegetable dish or a light, meatless main course. Choose cucumbers that are evenly rounded and no longer than 7 inches, to fit vertically into a slow cooker. 8 cucumbers 5 tablespoons butter 2 tablespoons olive oil 1 large onion, chopped 2 tablespoons chopped green onions 1/4 pound mushroom Salt Several grinds black pepper Nutmeg 1 cup broth (chicken or beef)

Scrub cucumbers but do not peel. Cut off them stem an inch or so from the top and put aside. With a small knife and an iced tea spoon, hollow out cucumber to within 1/2 inch of the other end and discard seeds and pulp. Lightly salt inside of each and set vertically on cut ends to drain while preparing duxelles.

Melt butter in skillet, add olive oil. Finely chop and combine onions and mushrooms and saute in butter oil until just limp but not browned. Sprinkle sparingly with salt to taste, a little nutmeg and ground black pepper. Using fingers and a long-handled spoon, push filling into each cucumber. Set cucumbers vertically in slow-cooker, put on reserved cucumber tops. Add 1 cup chicken or beef broth, or water, and cook on "slow" or "low" setting 5 to 6 hours, checking at the end of that time for tenderness.

Serves 8 as vegetable side dish, 4 as main dish served with parsley-flecked vinaigrette tomato slices. For variety, halve the duxelles proportions and stuff four cucumbers with duxelles, and four with any favorite meat filling. NEW POTATOES IN CUCUMBER SAUTE (6 to 8 servings) 24 very new potatoes 3 tablespoon butter 1 teaspoon parsley, chopped 2 teaspoons chopped greens onion tops 5 tablespoons flour 1 1/2 to 2 cups chicken broth 1 teaspoon salt 2 teaspoons white wine vinegar 3 large cucumbers 1/2 cup sour cream 2 tablespoons chopped fresh dill, or 2 teaspoons dried Chopped parsley to taste

Using a stiff brush, serub unpeeled potatoes. Peel cucumbers and cut them in half lengthwise. Remove seeds, cut cucumbers into 1/4 slices, put in bowl and lightly salt alternate layers.

In a skillet large enough to hold potatoes in a single layer, bring to boil enough salted water to cover uncovered high heat 25 minutes or until barely tender enough to be pierced with a fork. Drain well and leave to dry and stay warm between layers of paper towels. In the same skillet, drained and dried, melt butter, sprinkle in chopped green onion and parsley and stir a second or so. Sprinkle flour into mixture a tablespoon or more at a time, incorporating flour and butter mixture after each addition. Gradually stir in 1 1/2 cups chicken broth (reserve the other 1/2 cup) and let sauce simmer 5 minutes, stirring occasionally. Add salt and vinegar and bring to just below a boil.

Drain cucumbers thoroughly, pat dry and add them to sauce. Simmer 5 minutes, stirring to coat cucumbers. Add potatoes, stir to coat, cover skillet and leave on lowest heat for 5 minutes or until potatoes are thoroughly heated. Add sour cream, blend well, and leave another few minutes to heat through; do not allow to boil. At this point, if sauce seems too thick, carefully stir in remaining hot chicken broth until sauce is correct consistency. Serve sprinkled with chopped dill, or dried dillweed, and chopped parsley. CUCUMBERS COOKED WITH PEAS (6 servings)

The expediency of combining two summertime vegetables in this simplest of cooking methods offers the freshest of summer's tastes. 2 large cucumbers, cut in chunks (about 3 cups) 3/4 cup water 2 cups fresh peas, shelled 1 rounded teaspoon chickes bouillon granules

Peel cucumbers, seed them and cut into small chunks. In large skillet bring water to boil, sprinkle in bouillon and add cucumbers spread in one layer. Cover, lower heat to simmer and cook cucumbers 7 minutes. Stir in peas, cover again and cook barely 5 minutes, just until both cucumbers and peas are tender but firm.

Note: 2 packages plain frozen peas, slightly thawed to separate, may be substituted for fresh peas. Follow same cooking directions.