“Traditional sours often intimidate people for two reasons: They seem complicated to make, and they include raw egg whites. Considering the ease of this recipe, and the fact that egg whites are actually high in protein and low in calories, there should be nothing stopping you from trying this classic today.” – Chris Jacks
Pour egg white, whisky, lemon juice and simple syrup into cocktail shaker. Do not add ice. "Dry shake" for 20 seconds to froth the egg white.
Add ice to cocktail shaker and shake again for 20 seconds. Strain into your cocktail glass. Consider adding a few drops of either bitters or vanilla extract on top.
Simple syrup is (as its name implies!) as simple as preparing a 1:1 mixture of sugar and water. Heat one cup of water to near boiling, then add one cup of sugar. Stir until sugar is dissolved. Refrigerate for up to three weeks.
A nice variation of this cocktail is the New York Sour. Follow the recipe above, but finish by floating 1 oz of red wine on top.