The national cocktail of both Peru and Chile (don’t ask them to agree on who did it first), the Pisco Sour is a bright, frothy, and utterly refreshing drink that shows off the unique flavor of pisco, a South American grape brandy. Shaken with lime juice, simple syrup, and egg white, and finished with a few drops of bitters, it’s tart, smooth, and lightly creamy, with a meringue-like foam that makes every sip a little celebration.