Chill your glass in the freezer or simply add ice to it. In a shaker, add the lime juice, the simple syrup, «the egg yolk» and the pisco. Dry Shake for about 10 seconds. Next, add ice to your shaker and shake again 10 to 15 seconds. Strain into your chilled coupe. Add a few drops of Angostura bitters to the froth.
Enjoy!