What a dilemma this has been!? Lemon or Lime!? In Spanish class they tell you lemon means limón. So when people translate recipes, naturally a Pisco Sour is made with limón and thus in North America it is made with a lemon – right?
What Peruvians call LEMONS are actually LIMES and vice versa. Therefore, a Peruvian lemon is in fact a North American Persian lime.
If you ever see a recipe calling for lemons, don’t be fooled, it was just lost in translation. A Peruvian recipe very rarely calls for Lemons, in fact, I’ve spent a lot of time in Peru and I have very rarely seen an actual yellow lemon.
So, let’s reiterate; a pisco sour is NEVER EVER made with lemons.
They should be made with Persian limes and in fact, key limes (the little ones) are more sour then the Persian limes and really aren’t optimal for pisco sours. The perfect pisco sour ingredient is a nice round, ripe, slightly squishy Persian lime. The best ones have skin that is slightly taught and smooth (you can’t see or feel the normal ridges that citric fruits normally have, think an orange peel), this means they are ready to be squeezed into your perfect cocktail.