What Makes A Cocktail A Sour?
A cocktail is classified as a sour if it contains a combination of sweet (usually in the form of a syrup or juice), sour (usually in the form of citrus juice), and alcohol. The sour element is what gives the cocktail its name, and can be achieved through the addition of lemon or lime juice. A sour can also be modified with the addition of other ingredients such as egg white or bitters, but the key to a sour is the balance between the sweet and sour components.