While most recipes for the Pisco Sour call for 2 ounces of pisco, the delicate flavors of this distilled spirit are easily muddied when combined with stronger flavors like lime juice. This build uses a larger proportion of this base spirit, which allows more of its nuance to shine through.
The foam that results from including an egg white in a cocktail can often take on an unappealing aroma as the drink sits. Because of this, the foam is often garnished with something that smells more pleasant: a few drops of bitters or tincture, or a spritz of oil from an expressed citrus peel.