Elegant dining in the open air

Is there anyone who doesn't like to picnic?

Simone Beck, co-author with Julia Child of ''Mastering the Art of French Cooking,'' remembers elegant picnics when she was a girl growing up in France. There was chicken in aspic, each piece wrapped in a large leaf of romaine so you could eat it without a knife and fork; ''bouquets,'' which were little pink shrimps eaten with buttered bread; Pont L'Eveque cheese, sweet pears, and a chocolate cake. Her mother and father had special low-folding chairs, and the butler-chauffeur was there to serve everyone.

Most picnics are much less formal, of course, and choosing the food to take along is half the fun. Keep the dishes simple, and be sure they are easily portable and won't suffer from traveling to the picnic site.

Here is a simple menu for a meal in the open air. Either the pasta salad with crisp vegetables or fresh asparagus with a mimosa vinaigrette will go nicely with garlic-scented roast chickens, a classic French dish that can be made a day ahead and served cold. Bring along some baguettes from a bakery and, if you wish, a few cheeses to serve with it.

Dessert can be as simple as a basketful of fresh strawberries, especially delicious with a small dish of sour cream and another of brown sugar to dip them in. For a more elegant ending to a summer feast, serve a frozen raspberry souffle accompanied by buttery, shell-shaped madeleines. Picnic Roast Chicken 2 broiler-fryer chickens, about 3 pounds each 2 cloves garlic, cut in half 4 whole cloves garlic, peeled 6 tablespoons butter or margarine, melted 1 teaspoon each salt and pepper 1/2 teaspoon each thyme, oregano, sage, and basil Watercress sprigs, optional

Preheat oven to 425 degrees F. Remove giblets from chickens and reserve for another use. Rub skin of each chicken with 1 clove of cut garlic. Then stuff each body cavity with 3 cloves of garlic, including the cut ones. In small bowl, stir together butter, salt, pepper, thyme, oregano, sage, and basil. Spoon 1 tablespoon of butter mixture into body cavity of each chicken. Tie legs of each chicken together. Brush chickens generously with butter mixture.

Place chickens breast up in roasting pan. Set in middle of oven and cook for 15 minutes, turning on the left side after 5 minutes, and the right side for the last 5 minutes, basting each time. Reduce oven to 350 degrees F.

Leave chicken on its side and baste every 10 minutes. After 20 minutes, turn onto other side and continue cooking for 20 minutes, basting again. Finally, turn breast up and continue cooking and basting until done, about 20 minutes more. Prick the drumstick with a fork and juices should run clear. If not, roast another 5 minutes and check again.

Let cool slightly, cover loosely with foil, and refrigerate until well chilled or until next day. Garnish with watercress, if desired. Serves 6 to 8. Cold Pasta Primavera 1 pound pasta, such as spirals, butterflies, or medium shells 4 cups fresh vegetables, including two or more of the following - broccoli, green beans, peas, summer squash, and zucchini 6 medium tomatoes 3/4 cup olive oil 1 large clove garlic, finely chopped 1/2 cup fresh basil, chopped 1 teaspoon salt Pepper

Cut broccoli into florets. String beans and cut into 1-inch lengths. Shell peas. Quarter summer squash and zucchini and cut into 1-inch sections. Cook all vegetables until just crisp in boiling, salted water. This should take only about 3 minutes, a little longer for beans. Drain vegetables and rinse in cold water.

Peel, seed, and cut tomatoes into 1-inch cubes. In frying pan, heat 2 tablespoons olive oil. Add garlic and tomatoes and cook gently for 3 minutes. Season with salt and freshly ground pepper. Cook pasta in large amount of salted water until barely tender. Drain and rinse in cold water. While still warm, toss with 1/2 cup olive oil. In large bowl, stir together pasta, tomatoes, and vegetables. Finally, add fresh basil and toss lightly. Serves 8. Cold Asparagus Mimosa 2 pounds very fresh tender green asparagus 2 teaspoons salt, or to taste

Break off end of each piece of asparagus, leaving only the tender green, then peel lower end of stalks. Wash stalks well and tie them together into four bundles.

Boil 2 quarts of water in a pot that will comfortably hold asparagus. Add salt. Add asparagus and cook 4 to 7 minutes or until tips are tender. Remove bundles carefully and spread out to dry on a towel, then chill in refrigerator while making sauce. Mimosa vinaigrette 2 eggs, hard-boiled About 3 tablespoons mixed fresh chervil, parsley, and chives, minced (if using dried herbs, use 1 teaspoon of each) 3 tablespoons wine vinegar 1 1/2 tablespoons Dijon mustard About 10 tablespoons olive oil Salt Black pepper, freshly ground

Put hard-boiled eggs through food mill to obtain a ''mimosa.'' Mix mimosa with herbs and set aside. In bowl, blend vinegar and mustard, then very gradually beat in oil, using a whisk. Season highly with salt and pepper.

When asparagus is cold, pour part of dressing over it, and sprinkle tips with mimosa and herbs. Serve remaining dressing in a sauceboat. Serves 8. Raspberry Macaroon Mousse 2 10-ounce packages frozen raspberries, thawed 2 cups heavy cream 2 egg whites 1/2 cup sugar 2/3 cup crisp macaroon crumbs

Puree raspberries in blender. Strain and pour into a mixing bowl. Whip heavy cream until stiff and fold into raspberries. Beat egg whites until stiff. Gradually beat in sugar. Fold egg whites into cream mixture. Spoon into 1 1/2 -quart souffle dish or other mold. Freeze for 1 hour or longer.

Cover mousse with macaroon crumbs. Swirl with knife to form streaks. Freeze until firm. Place in refrigerator 2 hours before serving, or carry to picnic site in cooler. Serves 8. Madeleines 6 tablespoons unsalted butter 6 tablespoons flour Pinch of salt 2 eggs, at room temperature 1/2 teaspoon pure vanilla extract 1/3 cup granulated sugar Grated rind of 1/2 lemon Butter and flour for coating madeleine pans

Preheat oven to 350 degrees F. Butter each mold of madeleine pan, then sprinkle with flour and shake out excess. Set aside.

Melt butter in small saucepan over low heat. Set aside and let cool to lukewarm. Sift together flour and salt. Break eggs into medium-size bowl and beat until quite thick and lemon colored. Add vanilla. Gradually add sugar while beating constantly. Beat until light and fluffy.

Sift 1/3 of flour over batter. Add lemon rind and 1/3 of butter. Fold in quickly, then add remaining butter and flour in two portions.Spoon batter into molds, filling each about 3/4 full. Immediately place in oven and bake 15 to 18 minutes, or until lightly brown. Remove from oven and use a small spatula to loosen each madeleine from its mold. Cool on wire rack. Makes about 18 madeleines