Onions are a fundamental ingredient that gives background sweetness and depth to an endless number of soups, sauces, stews, and vegetable dishes. Different kinds of onion come to market at different times. The most common onion—the yellow onion with brown, dry, papery skin—is held in storage and available year-round. Spring onions—fresh onions with bulbs and intact green tops—are harvested and sold in spring. They are tender and mild and wonderful to cook with. The sweet onion varieties (which include Walla Walla, Maui, and Vidalia onions) start to mature in the early summer; these are big onions with pale yellow papery skins, but they do not store well. The height of summer is also the height of onion season, and the market is crowded with scallions and recently harvested onions. (Scallions have green tops, like spring onions, but they lack bulbs.) Look for spring onions and scallions that are bright and shiny with fresh-looking greens. Roots should be fresh and white, not withered. Dry, cured onions should be hard, with crackly, papery skins. To prepare spring onions, trim away the green tops, root end, and any dry or damaged outer layers. To prepare cured onions, make shallow cone-shaped cuts to remove the stem and root ends. Unless you want to slice horizontal onion rings, cut the onion in half lengthwise and peel away the papery skin (it is much easier to peel an onion after it has been cut in two). Tiny onions are easier to peel if you soak them for a minute or two in warm water to hydrate their skins; just do this right before you peel them. Slice or chop onions right before you need them: onions oxidize and start losing their best flavors soon after they are cut. Use a sharp knife, to avoid mashing and bruising them. If they are to be used for a salad, submerge sliced onions in ice water to preserve them. (This will also help tame the raw flavor of a hot, pungent onion.) The sweet and salty combination of onion and anchovy is particularly delicious, especially in an Onion Tart (page 177).

Ingredients

　　Peel firm, juicy onions and slice them crosswise 1/4 inch thick. Figure 2 to 3 slices per person. Brush a baking sheet with olive oil and place the onion slices on it in a single layer. Season the slices with salt and turn them over. Brush the exposed sides of the onions with more oil, season with salt, and bake them in a 375°F oven for 30 minutes or until tender and browned on their undersides. Serve the onions as is, or marinate them in a spoonful or two of vinaigrette. These are good warm as a side vegetable and at room temperature as part of a salad or antipasto plate.

　　The Art of Simple Food