This is the classic 3:1:1 recipe which works with 1:1 strength simple syrup. If you are using a 2:1 syrup, cut back to a scant 1/2 oz.
As always, shake long and hard to fully break up the egg white and to create a lucious foam.
You can use a Champagne coupe or other up glass to serve a Pisco Sour as well. Just make sure to chill the glass.
Peru and Chile consider the Pisco Sour their national drink.