What ingredient is optional in an Old Fashioned cocktail?

In the Old Fashioned cocktail, the cherry is considered an optional ingredient. The classic recipe traditionally consists of whiskey, sugar, bitters, and a citrus twist (often an orange peel). While the inclusion of a cherry can enhance the drink's presentation and add a touch of sweetness, it is not fundamental to the cocktail's identity.

The essence of an Old Fashioned lies in its simplicity, showcasing the whiskey, which is the primary spirit, and the bitters which provide depth and complexity. Some variations may include soda or other garnishing elements like a cherry, but the drink maintains its core flavors and characteristics without it. Consequently, the cherry can be omitted without compromising the integrity of the cocktail as a true Old Fashioned.