Sidecar, Whiskey Sour, Margarita, Daiquiri. These drinks have something fundamental in common: they're all sours. Sours are fundamental cocktails. Take a base spirit, add citrus, and polish it off with a sweetener, usually (but not always) triple sec. Tweak the balance as you will, but sours made well are always delicious. Sidecar: brandy, lemon juice, triple sec. Whiskey sour: Bourbon, lemon, triple. Margarita: tequila, lime, triple. Daiquiri: rum, lime, simple syrup. Let's try a different base spirit: citrus vodka. To finish out the Sour Experience, add the requisite triple sec and citrus, in this case, lime. For variety, add another fruit flavor: cranberry, why not? The Cosmopolitan is a cultural touchstone because once upon a time, Dale DeGroff got one into the hands of Madonna at the Rainbow Room and it became the drink to be seen with. Then HBO and SJP, of course, made the drink ubiquitous and clichÃ©d. Nevertheless, sours are fundamental cocktails, and the Cosmopolitan is, simply stated, the best Vodka Sour around.