Which cocktail is known for containing egg whites?

The Pisco Sour is indeed known for containing egg whites, which are used to create a smooth, foamy texture that enhances the drink's mouthfeel and overall presentation. In a Pisco Sour, the egg whites lend a velvety quality and help to form a stable foam on top when shaken vigorously. This distinctive characteristic sets the Pisco Sour apart from other cocktails, making it not only visually appealing but also adding a unique richness to the flavor profile.

While the Whiskey Sour can also include egg whites in some variations, it is not universally associated with them as is the Pisco Sour. The Mai Tai and Margarita do not traditionally incorporate egg whites into their recipes, focusing instead on their distinct combinations of spirits and mixers. Therefore, recognizing the Pisco Sour as the classic cocktail that prominently features egg whites is key.