By John Gerber
1½ oz. Pisco
½ oz. Elderberry Shrub
½ oz. Fresh Lime Juice
½ oz. Simple Syrup
1 each egg white - (caveat emptor)
3 dash Bitters
Combine the first five ingredients in a dry shaker.
Shake vigorously to develop a froth.
Add ice and shake again until well chilled.
Strain into a chilled cocktail glass.
Dash the bitters over the frothy top.