Along with such staples as onions and potatoes, the kitchen of any good cook surely contains an airy basket of lemons.

The tangy flavor of lemon can elevate ordinary fare to elegant fare. Also, the clean, cirtrus aroma of lemons can clear stale air. Put a handful of lemon peel on a piece of aluminium foil in a warm oven and let it heat gently for a short time. The air will soon be fresh and fragrant. Another way to sweeten household air is to put a few curls of lemon peel in with a favorite bowl of potpourri. Or, stick whole cloves into a large lemon, tie it with a pretty ribbon and hang it in a closet to dispel mustiness. These old-fashioned pomanders are easy to make and useful in many spots around the house.

When boiling cauliflower, toss in half a lemon to keep the cauliflower white and to cut down cooking odor. Some other lemony tricks to try: Rub eggshells all over with juice from a cut lemon to prevent the shells from cracking when the eggs are boiled. After handling fish, or after chopping onions or garlic, rid hand of odor with lemon juice. To fade stains on butcherblock counters, rub them with lemon juice and salt. Copper can also be polished with lemon juice and salt. These are only a few ways the lemon is helpful.

The lemon is at its best in cookery. Not only does fresh, plain lemon juice bring out flavor, but it adds piquanace to sauces and gravies. It works masterfully with fish, meat and poultry, is the very essence of a wide variety of deserts and condiments. It can blend with other ingredients to form a new ingredient. For example, lemon juice with butter and garlic is a unique, whole "new" flavor of its own.

When buying lemons, it is good to know that the largest are not always the best. In fact, the small, oval, thinskinned lemons are the most satisfactory of both juice and pulp. The best way to store them is at room temperature. They will keep for up to a week. Storing them at room temperature assureas a maximum of juice and development pf flavor. A natural woven or wire basket or wire lemon tree (available at kitchen shops) is ideal for storage. Such containers allo the air to circulate around the fruit, thus retarding spoilage.

If lemons must be sotred longer than a week, refrigerate them after they have ripened fully. But before using a refrigerated lemon, drop in in warm water for a few minutes. Lemon juice can be frozen successfully. Freeze it in ice cube trays, and than transfer lemon cubes to plastic bags. (In summertime, lemonade frozen this way is also handy for adding sparkle to coolers and tea.)

Take a hint from some of the best cooks, who keep a few of these lemony quick-tricks up their sleeves: Keep a jar or lidded crock of lemon butter in the refrigerator at all times. To make it, just whip lemon juice and a dash of salt into softened butter. This will keep five to seven days in the refrigerator. It is handy for swirling into gravies, adding to freshly cooked vegetables (try it on green beans or carrots) and for basting fish and meat. Vary the lemon butter by adding a favorite herb, such as thyme or rosemary. Another trick is to keep finely chopped garlic, parsley and grated lemon rind in a jar in the refrigerator. When sauteeing veal or chicken breasts, add a generous sprinkling of this mixture to the pan juices, along with a big squeeze of lemon juice. This mixture does not freeze well, but any lemon butter can be frozen. Roll it into sausage-shape, and wrap these in foil and freeze. When needed, slice off as much as desired, rewrap and put the remainder back in the freezer.

Since shape, texture and color are so important to cuisine, this trick with lemons tastebuds. Serve seafood or fish salad in whole lemon shells. Cut a lid off the top of the lemon, and a disc off the other end so it will stand firmly upright on a serving dish. Scoop out the pulp (save it to use later) and fill the lemon with seafood or fish salad, put the lid back on, garnish with parsley and cherry tomatoes and serve with cocktail forks, as a first course or luncheon entree. These filled lemons are very attractive when grouped on a serving plate and surrounded with generous bunches of parsley of cress.

The role of the lemon in good cooking cannot be overstated. To add tang to cooking and sunshiney aura to the kitchen, squeeze a lemon. TAPANADE (Tuna-Anchovy Sauce) (Makes about 1 1/2 cups) 1/4 cup capers, drained 1 can (2 ounces) anchovies, drained 1 can (7 ounces) tuna, drained 15 Italian black olives, pitted Juice of 2 lemons 1/4 cup olive oil 1 tablespoon brandy

Place all ingredients except olive oil and brandy in a blender and blend until pureed. Keeping the blender on, add the olive by droplets until the mixture is thick and creamy. Pour into a serving dish and stir in brandy. This sauce is a good dip for raw vegetables, or as a garnish for broiled fish, pork or cold boiled beef. BAKED RED SNAPPER WITH LEMON-ONION SAUTE (4 servings) 4 tablespoons butter 3 large yellow onions, chopped 1lemon, peeled, seeded and chopped 1/3 cup parsley, finely chopped 2 to 3 sprigs fresh thyme, or 1/6 teaspoon dried One (4 pound) red snapper, boned, but left whole Salt and freshly ground pepper to taste 3/4 cup dry white wine 8 scrubbed new potatoes, with skins 1tablespoon chives, chopped

Preheat the oven to 350 degrees. In a large skillet melt the butter, add the chopped onion and lemon, and saute over a low flame 5 to 8 minutes, until the mixture is thick and glazed. Add the chopped parsley and the thyme, stir and take off heat.

Butter a large oval baking dish and place the red snapper in the midle. Sprinkle fish inside and out with salt and pepper. Stuff with the onion-lemon mixture. Pour the white wine overt the fish and bake in the preheated oven 20 minutes, basting from time to time, with the pan juices. After 20 minutes, add parboiled new potatoes and continue baking until fish is done -- about 15 minutes. Place fish on heated serving platter, sprinkle with chives and encircle with potatoes. POULET AU CITRON (Lemon Chicken) (4 servings) 4 tablespoons butter 2 lemons 4 chicken breasts, boned, skinned and split 1/2 pound emmenthaler or gruyere cheese

Preheat the oven to 350 degrees. Cut one whole lemon and half of the other lemon into thin slices, and stew in the bottom of a baking dish. Add butter and heat over low flame until butter is melted. Remove from heat and place chicken breasts which have been folded ot from tiny mounds on top of the lemon slices. Squeeze juice from remaining lemon half over chicken.

Bake in the preheated oven for 20 minutes, basting once or twice. Meanwhile, slices the cheese into small, thin pieces. When the 20 minutes are up, remove the chicken from the oven and place the cheese on top of the chicken breasts. Return to the oven for about 5 minutes, or until the cheese melts and coats the chicken. PASTA SAUCE (2 servings) 2 tablespoons butter 3 tablespoons scallions, chopped 2 fresh mushrooms, julienned 1 teaspoon salt 2 small tomatoes, peeled, seeded and chopped 1/4 cup lemon juice 1 cup heavy cream 1/2 cup chicken stock 1/2 pound linguine, cooked al dente

Melt butter in a skillet, add scallions and saute over low heat for 1 minute. Then add mushrooms and salt. Cook gently for a few more minutes and add tomatoes. Continue cooking until tomatoes have melted into other ingredients. Add lemon juice and chicken stock and raise heat, continue cooking until liquid has been reduced to about 1/4 cup. Add cream and continue cooking until sauce has thickened. Divide cooked, drained linguine between two large plates and pour sauce into the center of each mound of pasta.