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The more research I do on pisco sours, though, the more confusing things become. For one, there’s the fact that Chile and Peru both claim pisco as their national spirits, and make it slightly differently. In both countries pisco is distilled from grapes—essentially, they make wine and then run it through a still (I wrote more about exactly what pisco is here). But in Chile, the pisco is often (not always) aged in oak barrels, and water can be added after distillation to bring the spirit down to 40 percent alcohol—though again, this isn’t always done; pisco can be bottled at anywhere from 30 to 50 percent alcohol. Peruvian pisco has to be bottled at distillation strength, and is never aged in wood.

The funny thing is that the pisco sour is the simplest of cocktails: it involves pisco, lemon or lime juice, sugar, and ice. In Chile, egg white and bitters are optional. But what kind of sugar? Lemon or lime juice? Should the ice be blended, or shaken with the drink and then strained?

  • Julia Thiel
  • I think that’s the lime pisco sour on the left and the lemon on the right. They looked pretty much identical, though.

I used a fairly standard pisco sour recipe: two parts pisco (I used Capel Doble Destilado), one part lemon or lime juice, one part simple syrup, shaken with ice and then strained. (Many recipes call for three parts pisco rather than two, but both are common.) The difference was striking: the cocktail with lemon tasted smoother, sweeter, and more tropical—it seemed more citrusy, somehow. The one with lime was brighter and more sour, with a little bite, and I ended up preferring it.

  • Julia Thiel
  • Merquen syrup

Anyway, the book didn’t include a recipe for the merquen syrup, so I put a couple tablespoons of the spice into a pot with a cup of sugar and a cup of water, heated it until it boiled, then turned off the heat and let it cool for about half an hour before I strained out the merquen. The recipe was almost identical to the other one, except that it called for Control C pisco and lemon instead of lime juice (as with the other recipe, I omitted the egg white and bitters). The merquen syrup made the cocktail smoky and a little earthy, a nice counterpoint to the bright citrus flavors. I was afraid it would be too spicy, but instead the syrup gave it a gentle heat that built over time.