A Pisco sour is commonly prepared with egg white, lime (or lemon) juice, and simple syrup. The Peruvian version includes bitters while the Chilean version usually does not.
Pisco, a grape brandy, is the key ingredient in the national cocktail of both Peru and Chile, the Pisco sour.
On May 16, 2013, TTB will publish a final rule in the Federal Register amending the distilled spirits standards of identity regulations to include Pisco as a type of brandy and a distinctive product of Peru and Chile. This final rule will be effective on July 15, 2013.
To learn more about this regulatory amendment, read the press release (TTB Press Release FY-13-08): TTB Amends the Distilled Spirits Standards of Identity Regulations to Recognize "Pisco" as a Type of Brandy and a Distinctive Product of Peru and Chile