Derek Brown is a Washington DC area mixologist. He owns the bar The Passenger, as well as the 18 seat Columbia Room housed in the same building. Derek treats his cocktail menus much the way a private chef would, parsing courses and pairing cocktails with food.
Egg whites are frequently used in cocktails, including the Pisco Sour.
1 egg white
2 1/2 oz Pisco Capel
1/2 oz simple syrup
3/4 oz fresh lemon juice
Angostura Bitters
In cocktail shaker filled with ice, combine egg white, Pisco, simple syrup, and lemon juice. Cover, shake vigorously for 15 seconds, and strain into six-ounce cocktail glass. Top with a few drops of bitters.
(From Epicurious)