A good caipirinha has all the nostalgic power of Proust's madeleine; one sip of this Brazilian bombshell and you're back in Ipanema. Although at last count it was the most-quaffed cocktail in the world, here in the U.S. the caipirinha is still somewhat exotic. As such, the local opportunities for cachaça-fueled brain travel are limited. Pesce, better known as a purveyor of fresh small-plate seafood, mixes up an evocative version. A couple of chopped-up limes are mashed together with sugar, ice, and a slug of Pit? cachaça, a sugarcane spirit that is to rum as tequila is to tap water. After downing one or two of these sweet, potent batidas, you'll be flying down to Rio without leaving Polk Street.