BY MIDSUMMER the food you bring to a picnic is as predictable as the pests that fly overhead. While there is nothing entirely new under the August sun, a variation on familiar themes can make a picnic interesting.

Tapenade, a dull-looking but delicious dip, makes a nice accompaniment to fresh vegetables. Empanadas are an excellent, portable main course. They are "the hot dog of Latin America," according to an Argentine friend Ana Channell, who gave me her family recipe.

Chicken baked in the style of spare-ribs is a welcome relief from fried. Although there are many recipes for bean salad, this tangy one is my favorite. Chocolate chip cookies are a fine way to end a picnic. This recipe is quickly made up in the food processor.

Everything is finger food so you don't have to worry about packing silverware and plates. Just include lots of napkins.

TAPENADE

(Makes about 3 cups) 1 can (7 ounces) water-packed light meat tuna, drained 24 large pitted black olives (1/2 of a 6-ounce can) 1 can (2 ounces) anchovies, drained 3 tablespoons capers, drained 2 medium cloves garlic 1/3 cup fresh lemon juice 1/3 cup olive oil 1/4 teaspoon black pepper or to taste Vegetables such as cauliflower, zucchini, carrots, celery and cucumbers, cut into bite-size pieces

Put tuna, olives, anchovies, capers, garlic and lemon juice in food processor fitted with steel blade and work until fairly smooth. Stir in olive oil. Add pepper. Refrigerate. Use as a dip for vegetables.

Make a day in advance, if possible, to allow flavors to blend. Keeps about 1 week.

ANA CHANNELL'S EMPANADAS

(Makes about 24)

Meat Filling: 1 medium onion, finely chopped 1/4 cup (1/2 stick) butter 1 1/4 pounds ground chuck 3/4 teaspoon salt or to taste 1/4 teaspoon black pepper or to taste 1 tablespoon plus 1 teaspoon ground cumin 1/4 teaspoon cayenne pepper or to taste 2 hard-cooked eggs, coarsely chopped 1/3 cup raisins 1/3 cup green olives (without pimiento) coarsely chopped

Pastry: 3 1/2 cups flour 1/2 teaspoon salt 3/4 cup lard 1 cup ice water (about)

Glaze: 1 egg yolk 1 tablespoon milk

To make filling, cook onion in butter over moderately low heat until soft, about 7 minutes. Add ground chuck and cook until redness is just gone. Add salt, pepper, cumin and cayenne. Let cool completely. Mix in eggs, raisins and olives.

To make pastry, combine flour and salt. Cut in lard. Add water gradually, tossing with a fork until dough just holds together, but is not wet or sticky. Turn out onto a floured surface and knead lightly. Let rest for 10 minutes. Divide into thirds. Roll each piece out as thinly as possible and cut into 4- or 5-inch rounds, using the top of a canister or a small sharp saucepan lid to make the shapes. Dust each round lightly with flour, stack and set aside.

Put about 2 tablespoons of filling in the center of a pastry round. Moisten the edge by dipping your finger in cold water and running it around pastry. Fold pastry in half and press to seal it. Press it again with the tines of a fork. Pierce top once to allow steam to escape during baking. Repeat this procedure until all rounds and filling are used up.

To make glaze, beat egg yolk and mi lk together.Brush empanadas lightly with glaze. Put on a lightly greased baking sheet. Bake at 400 degrees until browned, about 17 minutes. Serve warm or at room temperature.

BEAN SALAD

(6 to 8 servings) 1 can (16 ounces) chickpeas 1 can (16 ounces) pink beans or kidney beans 3/4 pound fresh green string beans or flat beans 1/2 cup olive oil 1/4 cup red wine vinegar 1/4 cup fresh lemon juice 1/2 teaspoon salt or to taste 1/8 teaspoon black pepper or to taste 1/4 cup chopped parsley (optional) 1 Bermuda onion, sliced thin (optional)

Rinse and drain chickpeas and pink or kidney beans in a colander. Put in a large glass preserving jar or other suitable container.

Cut off and discard tips of string or flat beans. Cut into bite-size pieces. Cook in about 2 quarts of rapidly boiling water until tender but still chewy, 7 to 10 minutes. Drain in a colander. Add to jar. Toss gently with olive oil, vinegar and lemon juice. Add salt and pepper. Garnish with parsley and onion slices if desired.

CHOCOLATE CHIP BARS

(Makes 25) 1/2 cup (1 stick) cold unsalted butter 1/3 cup granulated sugar 1/3 cup light brown sugar 1 teaspoon vanilla extract 1 egg 1 1/4 cups flour, stirred with a whisk then measured 1/8 teaspoon salt 1/2 teaspoon baking soda 1 package (6 ounces) semisweet chocolate chips

Cut butter into small pieces and put in food processor fitted with plastic blade. Add granulated sugar and brown sugar and work until barely creamed. Add egg and vanilla and work until just mixed.

Combine flour, salt and baking soda in a bowl. Add to batter and work until ingredients are just combined. Add chips and work until just distributed in batter. (Plastic blade will not chop them.)

Heat oven to 350 degrees. Grease an 8-inch square pan. Spread batter in pan, using a rubber scraper dipped in cold water. Bake until top is golden, about 18 minutes. Cut into bars while still warm.

BAKED CHICKEN DRUMSTICKS

(8 servings) 18 drumsticks 1 teaspoon salt or to taste 1/2 teaspoon black pepper or to taste 1/4 cup tomato paste 1 tablespoon white vinegar 1 tablespoon sugar 1/2 cup honey 1/2 cup soy sauce 1/4 cup dry vermouth

Arrange drumsticks in ridged foil pans or on a rack in a baking dish. Season with salt and pepper. Bake at 350 degrees until half-done, about 45 minutes.

Mix tomato paste, vinegar, sugar, honey, soy sauce and vermouth together. Baste drumsticks every 5 to 10 minutes with sauce until done, about 35 minutes more. Let cool. Refrigerate. Serve cold or at room temperature.