Though I use citrus zest all year long, I really appreciate its cheerful color and flavor during winter. Whether grated or cut into strips, the colorful outer peel of a lemon, lime, orange, or grapefruit brightens all kinds of dishes, savory and sweet.
A more complex flavor than juice. While citrus juice, especially lemon juice, has an important place in cooking and baking, it's a bit of a one-note wonder. I get more excited about the volatile and aromatic oils found in the skin of the fruit, which contain floral and tangy tones as well as a slight, sophisticated bitterness. I almost always add a bit of zest even if a recipe calls for juice only; zest underscores the citrus flavor and announces its presence both visually and texturally. In sweets, zest adds a colorful counterpoint to fresh berry fillings, dried fruit compotes, suave custards, and creamy frostings. Mellowed when baked, it insinuates its sunny personality into cakes and cookies. In savory dishes, a sprinkling of grated zest can brighten a rich stew, perk up a salad, and add zing to a stir-fry or vegetable sauté. Experiment with zest to discover your own uses for this versatile flavoring.
All citrus fruits are candidates for zesting. Lemons are the most popular. The zest from tangerines or blood oranges offers exquisitely flowery aromas. Grapefruits yield a wonderfully complex zest. Lime zest loses some of its kick when cooked, but added just before freezing to a sorbet or granita, it can't be beat.