A cocktail onion is a small pickled pearl onion, brined in vinegar, used as a garnish in cocktails such as the Gibson. It should be distinguished from the fresh pearl onion, the same small onion variety used unpickled in stews, braises, and roasted vegetable dishes. Cocktail onions have a mild, sweet-tart, faintly pungent flavor from the brine, with a firm, slightly crunchy bite. They're most often served on a cocktail pick alongside olives, or used to top hors d'oeuvres.