EACH YEAR the fragrance of ethnic food fills the Washington air on weekends after Labor Day. It is a season of festivals. Each has its share of music and dancing, games, parades, white elephant sales, face painting and carnival rides, but it's the food that makes them unique.

Preparation begins months in advance when members of local community groups and churches devote hundreds of hours to their ethnic specialities.

There are about 100 Fall festivals. The five attended are a representative sampling. The food is often excellent and always cheap.

Some of the best-tasting food is found at the Saints Constantine and Helen Greek Orthodox Church on 16th Street during September. One of the more spectacular food sights is the 10 lamb carcasses slowly roasting over an open pit, basted sporadically by the "lamb crew" with a perfect blend of lemon, oil, butter, oregano, salt and pepper. Forty whole lambs roasted over the open pit each for nine hours.

The wide assortment of pastries for sale was wonderful: koulouria and kourambiedes (hard cookies); galaktoboureko (custard pastry); karidopita (walnut-honey pastry); revani and finikia (honey pastries); tiropites (cheese blintzes); diples (batter, deep fried then dipped in honey); and, of course, there was baklava.

Lessons were offered in pastry making, Greek style. They were given by Helen Mantis, a church member who has spent a good part of the last 25 years making pastries for friends, family and the church.

"It's all in the handling of the phyllo dough" she said. Butter should be rendered and brushed lightly on the delicate dough with a 2-inch paint brush. Because it has a tendency to dry within minutes and tear, phyllo should be kept moist by laying a dry towel then a damp towel over the pieces not being used. Eggs, butter and honey are the essential ingredients in Greek pastry making. SAINTS CONSTANTINE AND HELEN TIROPITES (Cheese Pies) (Makes about 60) 1 (8 ounce) package cream cheese, softened 8 ounces cottage cheese, large curd 1 pound mild feta cheese, crumbled by hand 3/4 pound unsalted butter, clarified 1/4 teaspoon white pepper 1/4 teaspoon nutmeg 3 eggs, beaten 1/2 pound phyllo dough

Mix all ingredients except phyllo together, adding an additional egg if stiff.

Lay out phyllo dough 1 sheet at a time and cut into strips 1 3/4 inches wide. Brush each strip with melted butter. Fold over bottom edge 1/4 inch. Place less than a teaspoon of filling on that end of pastry strip and fold over one corner to make a triangle; continue folding pastry from side to side in the shape of a triangle (like folding the American flag). Place seam side down on baking sheet. Continue in this manner until pastry is used up. Then brush tops of pastires with melted butter. Bake at 350 degrees for 20 to 25 minutes or until pastries are golden brown and puffy on top.This recipe can be made ahead and frozen for up to 3 months. SAINTS CONSTANTINE AND HELEN KARIDOPITA (Walnut Cake) 1/2 teaspoon cinnamon 1/4 teaspoon nutmeg 1 1/2 teaspoons baking powder 1/4 cup zweiback crumbs, finely ground 2 cup walnuts, finely ground 6 eggs, separated 1/2 cup sugar 1/4 teaspoon vanilla 2 tablespoons Canadian whiskey Finely grated rind of medium sized orange Finely grated rind of medium sized lemon Syrup: 3/4 cup sugar 1 cup water Slice of lemon 1 cinnamon stick 1 tablespoon honey 1 tablespoon lemon juice

Mix cinnamon, nutmeg, baking powder and zweiback crumbs well. Add to nuts and mix. Beat egg yolks until light and lemon colored. Gradually add sugar, vanilla, whiskey and orange and lemon rinds. Beat egg whites until stiff and gradually fold into egg yolk mixture. Then fold in nut mixture. Bake in greased 9 x 12 baking pan at 350 degrees for about 30 minutes or until a toothpick inserted in the center comes out clean.

While the cake is baking make syrup. Place sugar, water lemon and cinnamon stick in a small saucepan. Bring to a boil and boil for 10 minutes. Remove from stove and discard lemon slice. Add honey and lemon juice.

When cake comes out of oven cut into diamond shaped pieces and pierce all over with a fork. Pour syrup over top while cake is still hot.

At Saint Sophia Greek Orthodox Cathedral on Massachusetts Avenue, Alexandra Glekas, 80, was the chief cook in the tiny, hot kitchen and the recipes were all her own. She had help from other parish members, most of whom were in their 70s, and all experts.

During this September festival you could choose from spanakopita (spinach-cheese pie), pastitsio (macaroni with meat and cream sauce), tiropites (cheese pies), manestra (rice), Greek salad, and gyro, souvlaki or meatballs on pita, and wash it down with Greek beer or wine. There was also a wide assortment of pastries.

Among the favorite dishes were chicken oreganato, stuffed grape leaves and loukoumades (honey deep fried dough-similar to a honey fritter.) SAINT SOPHIA CHICKEN OREGANATO A LA GLEKAS (2 servings) 1 (2 1/2 to 3 pound) fryer, split 1 tablespoon salt 1teaspoon pepper 1tablespoon oregano Juice of 1/2 lemon 1/4 cup oil

Wash chicken and pat dry. Mix salt, pepper and oregano together and rub on both sides of chicken. Mix together oil and lemon juice. Place chicken skin side down in baking pan and dribble oil/lemon mixture over top. Bake at 400 degrees for 15 minutes, turn and bake for additional 15 minutes.

Serve hot with manestra (Greek rice) and Greek salad.

Lebanese cooking is featured at St. George Orthodox Church on 16th Street.

Less well known than the other September festivals, there were no long lines and large crowds to contend with. While a lot of the pastries ran out on Saturday, the ladies in the Myrrh Bearing Society spent Saturday evening cooking up emergency supplies of the tasty baklawa, gribee (butter cookies), mamool (nut and sugar pastries) and kras ib seewa (date cookies),.

Main dishes included kibbee (lamb, bulghar, onions, pine nuts, onions), fatayer (spinach pies), hummous bi tahini (chick pea dip) lifit (pickled turnips and beets) and tabooli (cracked wheat, scallions, tomatoes, parsley seasoned with lemon and olive oil dressing. SAINT GEORGE BAKED KIBBEE (4 servings) 2 1/3 cups fine cracked wheat 2 pounds lean ground lamb 1 ground onion Salt and pepper, to taste 1 cup clarified butter (unsalted) Filling: 1 pound coarsely ground lamb 1 tablespoon butter 3 onions, finely chopped Salt, pepper and cinnamon, to taste 1/4 cup pine nuts

Wash cracked wheat; drain and let stand 1 hour. Add 2 pounds ground lamb, onion and salt and pepper. Grind twice. Add a little ice water to soften and knead. Set aside.

To make filling simmer 1 pound coarsely ground lamb in 1 tablespoon butter until all liquid disappears. Add onions, stir about 10 minutes. Add salt pepper and cinnamon according to taste. Mix well. Saute pine nuts in butter. Add to filling mixture.

To assemble spread 10 x 14 inch baking pan with a little clarified butter. Divide first meat mixture in half. Spread half of cracked wheat mixture in bottom of pan, using some water if necessary to make of spreading consistency. Add filling and cover with remaining cracked wheat mixture. Score halfway through with a knife into a triangular pattern. Loosen edges with spatula. Spread remaining clarified butter on top. Bake at 350 degrees for 35 minutes and then brown under broiler.

Adams Morgan Day, one of the larger events during September, is always busy. There were over 50,000 people this year. You could buy vegetarian platters, empanadas and tamales, barbecued chicken, steaks, fried plantains and South American soft drinks.

The real food treat came from a far corner of Columbia Road called Grover's North Carolina Barbecue. The entrepreneur, Grover Price, has been selling his barbecued spare ribs and chicken as a sideline to his job as manager of the F Street Flower Shop for 3 years.

His team, made up of family members and friends, has traveled across the country catering State fairs, festivals and private parties hoping to make enough money to open a restaurant. Price says his sauce has become so popular that offers have been made to sell it during the 1981 Carnival in Brazil and feature it at Oktoberfest in Germany.

Anyone who was patient enough to wait the 30 minutes to taste his food found it well worth the time. In one day Price sold over 300 pounds of chicken and 600 pounds of pork.

The Festival of American Folklife, held each year on the Mall across from the Smithsonian Institution (the sponsors), featured ethnic and natural foods and demonstrations in meat smoking and canning. This year it was held during October.

The best food was available from Scott's Barbecue a carry out restaurant on Mount Pleasant Street. There were barbecue beef sandwiches, spare ribs, cole slaw, Brunswick stew, collard greens, and sweet potato pie. Owner, John Sanders also brought along his delicious red beans and rice which are so popular in the area. SCOTT'S BARBECUE RED BEANS AND RICE (4 to 6 servings) 1 pound dry red beans 1 large yellow onion, chopped 2 bay leaves 1/2 teaspoon thyme 1 ham bone, with meat still on it 1 clove garlic, minced Salt and pepper to taste 1 cup long grain rice 2 cups chicken broth Sauce: 1 medium onion, chopped 1 clove garlic, minced 1 tablespoon butter 2 tablespoons tomato paste 1/4 teaspoon thyme Salt and pepper to taste

Pick through beans and soak over night in water to cover.

Next day put beans, onion, bay leaves, thyme, ham bone, garlic and salt and pepper in pot, add 6 cups water bring to boil and simmer, covered for about 2 hours or until tender. About 30 minutes before beans are done make rice substituting 2 cups chicken broth for the water. Add salt and pepper, to taste.

While rice is cooking make sauce. In a small frying pan saute onion and garlic in butter. Add 1/4 cup of liquid from beans, tomato paste, thyme, and salt and pepper. Simmer gently until heated through and add to beans. Stir in rice. Let stand for 30 minutes until liquid is absorbed. Serve hot.