Add the pisco, lime juice, simple syrup and egg white into a shaker and shake vigorously, without any ice. Add ice to the shaker and shake again, until well chilled.

Strain the cocktail into a chilled glass and if you wish, over ice cubes. Garnish with 3 to 5 drops of Angostura bitters. Using a straw or toothpick, swirl the bitters into a simple design and serve. Inspired by liquor.com.