In a blender combine the sugar, lime juice, and lime zest. Blend until the sugar dissolves. Add the pisco, egg white, and ice. Blend until combined and very frothy.
Notes
One thing I want to mention is regarding the egg white. Egg white is a pretty common ingredient in cocktails, especially older/classic cocktails. As air gets incorporated into the egg white, either by the blender like in this recipe, or from shaking a cocktail, it makes the egg white very frothy and will impart this texture to your drink.
If raw egg white just isn’t something you feel comfortable consuming though—no worries. I made this cocktail without the egg white as well, and it’s still very, very tasty. It will just make the consistency a little denser and more like a slushy (think frozen margarita).