Horsford's Acid Phosphate
Acid Phosphate can be used in cocktails to enhance the sour character. Because most cocktails use lemon or lime juice to balance sweetness, there is a tendency for many drinks to taste similar because of the fruity character of the citrus juice. Acid Phosphate is a perfect way to change the character of a drink.
Use ½ to 1 tsp of Acid Phosphate per drink, adjust to taste.