Both Peru and Chile lay claim to the pisco sour as their country's national drink, but it was an American expatriate from Salt Lake City named Victor V. Morris who first created this adaptation of the whiskey at his eponymous bar in Lima, Peru, in the 1920s. The registry at the Morris Bar was filled with high praise from visitors who raved about the signature drink, which used the namesake spirit, pisco, a clear brandy made from muscat grapes brought to Peru and Chile from the Canary Islands in the 1550s by Spanish conquistadors.
Recipes flip-flop between using lemon or lime juice, so experiment to see which way you prefer (I like lime). Rather than being mixed into the drink, the bitters are applied to the frothy surface of the drink as an aromatic garnish. Amargo Chuncho bitters out of Peru are billed as the authentic mate for your pisco sour. With a rather floral taste and scent, they lack the spice of Angostura, but if you have a bottle, definitely give them a shot.
Adapted from "Bitters: A Spirited History of a Classic Cure-All" by Brad Thomas Parsons (Ten Speed Press, 2011).
Combine all the ingredients except the garnish in a cocktail shaker and dry shake (without ice) for at least 10 seconds to fully incorporate the egg white. Add ice and continue shaking until chilled and strain into a chilled coupe or cocktail glass. Dot the top of the drink with the bitters (this is where an eyedropper to dispense your bitters comes in handy). Delicately run a toothpick or stirrer through the bitters to create a swirling pattern.