Cocktail Onion is a small, pickled onion often used as a garnish in cocktails. In the context of alcohol and cocktails, cocktail onions add a tangy, slightly sweet flavor that complements savory drinks. They are commonly used in classic cocktails like the Gibson, where the onion's briny taste enhances the drink's overall complexity. Cocktail onions can also be used in other martini variations and savory mixed drinks, adding a crisp texture and a burst of flavor.