THE MENU Soupe au Pistou Broiled Flank Steak Roasted Red Pepper and Watercress Salad Fresh Fruit Compote

THIS MEAL, while more light than heavy, has the substance that is wanted at summer's end. The soupe au pistou uses many of the fresh, local vegetables that are filling coops and truck stands. Beans, a little pasta and a potato add body, and the pistou, a heady amalgam of garlic, olive oil, fresh tomatoes and fresh basil, makes the soup wildly fragrant. The pistou is swirled into the soup just before it is brought to the table, and as the two combine the aroma is pure south of France.

The main course is one of my best standby recipes, a flank steak with a marinade rubbed into it and broiled quickly under high heat. It is delicious hot and perhaps even better cold. I have often made it for picnics. The salad that accompanies it plays the sweetness and softness of roasted red bell peppers, which are just on the market, against the sharpness and crispiness of watercress. The minced shallots in the dressing make a bridge between the two. Dessert is a compote of fresh fruits whose flavors are brought up by being poached separately in a vanilla-flavored syrup.

There is no one recipe for soupe au pistou. Beans, vegetables in various combinations, a pasta and the ingredients of the pistou itself are universal, although the proportions vary. Some recipes call for grated parmesan (too minestrone-like), saffron (too extravagant when the pistou overpowers it) and/or salt pork (unnecessary and complicated). Most classical recipes call for vermicelli as the pasta; but one of my friends, an excellent cook, hit upon ditalini, a short, fat macaroni available in some supermarkets and most Italian stores, which does not get mushy. Tiny pasta shells would also do. If, in winter, I could not get zucchini or yellow squash I would substitute any other kind of squash or some frozen peas, or I would increase the amount of those vegetables I could get. But if I have basil or frozen pistou, we will have this soup.

Had a friend not served us the flank steak for dinner, I would never have tried it on my own. I'd be too suspicious of the ingredients in the marinade. Despite the presence of soy sauce, which I tend to worry about, this dish is a sophisticated combination of flavors without a hint of fake-Chinesey-nothingness. I used to trim and score the flank steak the day before I cooked it and let it sit, with its marinade, wrapped in plastic in the refrigerator. But now I do this only if it suits me to do advance preparations, since it seems to make no difference whatsoever to the flavor if the marinade is put on immediately before it is cooked.

While flank steak is no longer the bargain it used to be, it is still a good value, since a little goes a long way, especially if the meat is carved very thinly, on the bias and against the grain. I know of no other cut on which I can amply feed eight on 2 1/2 pounds of meat. The hotter you can get your broiler, the higher the flame and the closer you can get the meat to it, the better it will be. A nice round loaf of French country bread would go well with both the soup and the meat.

Lovely fat red bell peppers are already at Straight From the Crate and the Bethesda Avenue Coop. The peppers are best when their skins are scorched off (either under a broiler, or held over a flame at the end of a long fork or, as I do it, roasted on a Creuset steak grill on top of the stove). Once roasted, peeled and seeded, these peppers freeze well and unmessily if they are placed in a single layer on a cookie sheet on waxed paper. After they are frozen, they can be decanted into plastic bags. They are wonderful for antipastos in the winter, or for peppers and anchovies. Here they are delicious with watercress and as an accompaniment to the flank steak. With all the vegetables in the soup au pistou, nothing more is needed for the main course.

The fresh fruit compote is as easygoing as the soup. You can use whatever you have, as long as it poaches well. I find it satisfying to combine late summer fruits. For green apples, I am cooking these days with rambos, a nice, tart Pennsylvania apple. I use macintosh, baldwin or jonathans for red apples in the fall, and always watch for the jonathans to come in since their season is short and their flavor and texture divine. The lovely little Italian prune plums are also appealing; these are the best cooking plums I know of and they add much in flavor and texture to this compote. I would not be heartbroken if I could not get peaches, since the other fruits are so good. This dessert can, of course, be made a day or two in advance, which is always an advantage.

SOUPE AU PISTOU (8 servings) 1 cup dried Great Northern beans A bouquet garni of 6 sprigs of parsley, 1 bay leaf and a few sprigs of fresh thyme (or 1/2 teaspoon dried thyme) Salt to taste 2 young zucchini, scrubbed but not peeled, and cut into 1-inch chunks 2 young yellow squash, scrubbed but not peeled, and cut into 1-inch chunks 1 large handful of string beans, ends snapped off and cut into 2-inch pieces 1 large onion, peeled and diced 2 medium-large carrots, peeled and cut into 1-inch chunks 3 small firm turnips (optional), peeled and cut into 1-inch chunks 2 tender stalks celery, cut into 1-inch chunks 1/4 cup olive oil 1/4 cup water 12 cups chicken broth 1 medium potato, peeled and diced 1/3 cup ditalini or tiny pasta shells For the pistou 8 fat cloves of garlic, peeled$ 2 large basil leaves 1/4 cup olive oil 1 1/2 pounds ripe tomatoes, scalded for 10 seconds, skinned, seeded and chopped Freshly ground pepper to taste

Soak the beans overnight in 3 quarts of cold water. The next day, drain them, add 2 quarts of fresh water, the bouquet garni and the salt. Bring to a simmer, skim and cook until tender, about 1 hour. Leave the beans in their liquid and set aside.

Place the vegetables, except for the potato, in a large pot along with the 1/4 cup olive oil and water. I use a seven-quart enamel-on-iron casserole. Cover and cook over medium heat for 15 minutes, stirring frequently until the water has evaporated. Do not brown or scorch the vegetables. Quickly add the chicken stock, salt to taste and diced potato and bring to a boil. Cook, uncovered, for 10 minutes. Add the ditalini or tiny pasta shells and cook 10 more minutes. The vegetables should retain some crunch. Remove the bouquet garni from the beans and add the beans and their liquid to the vegetables.

While the soup is cooking, make the pistou. Put the garlic and basil in a food processor with the olive oil. (If you use a blender, you will have to do this in two batches.) Process them briefly and then add the tomatoes. Process until the tomatoes are pure'ed. Add pepper. Bring the soup with the beans to a simmer. Beat the pistou into the soup and heat, but do not let it boil. Serve from the pot at the table.

Note: Do not add the pistou until just before serving.

BROILED FLANK STEAK (8 servings) 2 1-1/4-pound flank steaks 3 cloves garlic, crushed 1/4 cup soy sauce 2 tablespoons tomato paste 2 tablespoons peanut oil 1 teaspoon cracked black pepper 1 teaspoon oregano

Trim the flank steaks of any fat and score them on both sides in diamond shapes. Mix the remaining ingredients and rub them into the steaks. This can be done a day in advance and the steaks refrigerated or just before broiling. Preheat the broiler until it is very hot. Do not scrape off the marinade. Broil the steaks as close to the flame as possible for 4 minutes on each side. Carve in very thin slices, against the grain and on the diagonal. Serve hot or cold.

ROASTED RED PEPPER AND WATERCRESS SALAD (8 servings) 4 large red bell peppers 6 tablespoons olive oil 1 1/2 tablespoons lemon juice 1 tablespoon minced shallot Salt and pepper to taste 1 bunch watercress, washed and dried

Broil the peppers until the skins are blackened and blistered. Place them in a plastic bag and let them sit for about 10 minutes, or until they are cool enough to handle. Rub off the skins, seed the peppers and cut into strips. Mix the oil and lemon juice and add to the peppers. Add the minced shallot and salt and pepper. Set aside. Just before serving, place the watercress in a bowl, add the peppers with the dressing and toss.

FRESH FRUIT COMPOTE (8 servings) 2 1/2 cups water 1 cup sugar 1 vanilla bean, split 2 medium or 3 large red apples, such as macintosh, jonathan or baldwin 1 lemon 2 large or 3 medium pears, ripe but firm 2 large or 3 medium green apples, such as rambo or granny smith 4 ripe peaches 8 Italian prune plums 32 black grapes

Combine the water, sugar and vanilla bean in a saucepan and bring to a simmer over medium heat. Peel the red apples and add their peel to the syrup. Rub the peeled apples with the lemon and set them aside. Simmer the syrup over low heat for 10 minutes. Peel, quarter and core the pears and poach them in the syrup for about 5 minutes, or until they are just cooked. Remove the pears to a serving bowl, using a slotted spoon.

Peel the green apples and quarter and core them along with the red apples. Simmer these in the syrup until just cooked, about 4 minutes. Transfer them to the bowl. Drop the peaches in boiling water for 10 seconds, remove and slip off the skins. Halve the peaches and discard the pits. Poach the peaches in the syrup for about 6 minutes, or until just cooked. Transfer to the bowl. Wash the prune plums and add them whole to the syrup. Simmer for 8 minutes and transfer to the bowl. Finally, simmer the grapes in the syrup for 8 minutes and transfer to the bowl. Strain the syrup over the fruit and chill.