Add the pisco, fresh lemon juice, and simple syrup to a cocktail shaker without ice and dry shake vigorously for 10–15 seconds to emulsify the egg white.
Add ice and shake again hard for a further 10–15 seconds until well chilled.
Double strain into a chilled goblet glass.
Dash Amargo bitters over the surface of the foam as an aromatic garnish.
Always dry shake first - shaking without ice before adding ice dramatically improves the volume and stability of the egg white foam, giving you that signature thick, marshmallow-like head that defines a great Pisco Sour.
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