Red onions (Allium cepa) are crisp, colorful onions with deep reddish-purple skins, purple-white flesh, and a mildly pungent flavor that becomes sweeter and more mellow when cooked. Their distinctive color comes from anthocyanins concentrated primarily in the outer layers, while the bulb also provides quercetin and other flavonoids, fructans, and organosulfur compounds. Red onions are especially useful raw in salads, salsas, sandwiches, and grain bowls and can also be quick-pickled, grilled, roasted, sautéed, or caramelized.