Onions play a supporting role instead of starring on menus. Yet the behind-the-scenes impact of these powerful bulbs should not be underestimated; they may be the most universal of fresh flavorings. In every cuisine, a member of this fragrant family - whether yellow, white, red or green onions, leeks, shallots, garlic or chives - adds pungency and sweetness to salads, relishes, soups, stews or casseroles. Around the globe, the best cooks use onions with a liberal hand. The French, who refer to Lyon, their second largest city, as "the gastronomic capital of the world," identify its cuisine with the onion. When they speak of classic lyonnaise potatoes or artichokes, they mean that sauteed onions figure prominently in the dish. Standard Chinese stir-fry dishes start with green onions and garlic. Asian curry pastes begin with pureed onions, garlic or both. Moroccan cooks begin their tajines (stews) with generous amounts of onions which melt into a tasty sauce. Onions are the basis of the French vegetable mixture mirepoix (along with carrots and herbs) that begins many soups and stews. Hungarian goulash's rich brown hue stems from onions fried with paprika. Italian risotto and Middle Eastern rice pilaf start with sauteed onions. Fresh or charred onions lend their potent flavor to many Mexican salsas. Grilled or raw onions top American burgers and steaks and come with Indian tandoori chicken. Where would sandwiches be without raw onion slices? They accompany kebabs served in pita and sandwiches from pastrami to lox and cream cheese. To soften the bite of sliced raw onions, you can rinse or soak them briefly in cold water, then drain them and pat them dry with paper towels. Of course, onions are a must in Israeli salad, no matter what kind of onion you like. Sometimes I include both red onions for their sweetness and purplish hue and green onions for their herbaceous quality. Onions can also stand on their own. Europeans love glazed baby onions as a side dish and leeks vinaigrette as an appetizer. Americans start meals with fried onion rings and serve creamed onions with roast turkey. Around the Mediterranean, stuffed onions appear on feast-day tables. Onions are divided into two types - sweet and storage. Sweet onions are sold fresh, usually in spring and summer. Storage onions are cured or left to dry before going to market and are available year-round. White and red onions are often milder than yellow or brown-skinned ones, but there can be surprises. They don't leave you guessing for long; as soon as you cut the onion, its aroma tells you how pungent it is. Sweet onions taste sweeter than their more potent relatives when raw or briefly grilled. For most cooking, common storage onions are preferable; when cooked, they turn out sweeter than sweet onions. Red onions are often used raw so they keep their attractive color. Chopped green onions are great sprinkled into bowls of soup to perk up the flavor and are convenient for salads, as you can cut off the amount you need. Leeks are usually too tough to eat raw. When cooked, they acquire a milder, less sweet flavor than onions. They can be braised whole with broth and butter but are often cooked in boiling water like asparagus or are sliced and used in soups and stews. Onions contain good amounts of vitamin C, folate and fiber, as well as disease-fighting phytonutrients. Dana Jacobi, the author of The 12 Best Foods (Rodale, 2005), writes that the sulfur compounds that give onions their bite are good for the heart and advises: "raw onions are ideal from a health standpoint. But using them sauteed, grilled, roasted or boiled... still provides useful benefits. Have a heavy hand with onions. You can exceed the amount called for in most recipes without making them intrusive, especially if they're cooked." At the market, select onions that are dry, smooth, firm and relatively heavy, with skins intact and with no bruises or soft spots. Leeks should be flexible, with fresh green tops and unblemished white stalks. Keep onions in a cool, dry, dark, well ventilated area away from potatoes, which give off a gas that makes onions spoil more quickly; they will keep a few weeks. Delicate sweet onions and pearl onions are best refrigerated. Green onions should be refrigerated in an open plastic bag; they keep about 4 days. Refrigerate leeks loosely wrapped; they will keep up to a week. To minimize tears, chop onions near an open window or use a fan to blow the vapors away from you. Avoid peeling and cutting bulb onions in advance; exposure to air changes their flavor, or, as my mother-in-law used to say, "an evil spirit passes over them." ONION-SMOTHERED CHICKEN This gently spiced chicken with its rich onion sauce is wonderful with rice or noodles, which absorb the tasty juices. Serve it with lightly cooked green beans or broccoli. 1.4 kg. chicken pieces, patted dry salt and freshly ground pepper 2 Tbsp. olive oil 3 large onions, halved and sliced thin 1 tsp. ground cumin 1 tsp. ground coriander 1 tsp. paprika 4 large garlic cloves, chopped 3/4 cup chicken broth squeeze of lemon juice (optional) 2 Tbsp. chopped Italian parsley Parsley sprigs (for garnish) Sprinkle chicken pieces with salt and pepper on both sides. Heat oil in large deep saute pan or stew pan. Lightly brown chicken pieces in 2 batches in pan over medium heat. Remove with tongs to a plate. Add onions and cook over medium-low heat for 10 minutes or until softened. Return chicken to pan and add any juices from plate. Add cumin, coriander, paprika, garlic and broth. Cover and simmer, turning pieces once or twice, for 30 minutes for breast pieces and 35 minutes for leg and thigh pieces, or until tender. Remove chicken from pan but leave in onion. Skim fat from cooking liquid. Taste sauce and adjust seasoning, adding lemon juice if desired. Return chicken to pan. Cover and warm over low heat for 3 minutes. Serve hot, sprinkled with chopped parsley and garnished with parsley sprigs. Makes 4 servings. Faye Levy is the author of Feast from the Mideast (HarperCollins).