It would be easy to look past a Gibson, because, if it's well made, it's totally transparent. And so, with many other more elaborate and dark-colored concoctions to tempt me at Royal Boucherie in Old City (definitely try the Deshler, Gold Rush, or Oaxacan Penicillin), I completely underestimated the pure elegance of layered flavors that awaited in the frosty coupé of Gibsonia prepared for us by bar manager Dom Carullo. This classic drink of Plymouth gin and dry French Noilly Prat vermouth dates to 1898 San Francisco, where it was essentially a bitters-free version of the dry martini, according to author David Wondrich in his definitive tome Imbibe! (Perigee, 2007). The Gibson's signature pickled onion came later, Wondrich says, likely to distinguish it from dry martinis that were increasingly absent of bitters. But it is that onion that helps lift Carullo's Gibson to the next level. Unlike most bartenders, who fall back on the squishy, harshly tart onions of industrial provenance, Carullo pickles the little pearls himself in champagne vinegar with juniper, black caraway, coriander, and bay leaves. The effect of one in this drink is substantial, a stealthy allium depth charge that lends a vaguely roasty, vegetal note and that rides atop the gin's natural botanicals for a crystal-cold wave of savory flavors. It's a big step toward understated elegance for the dirty martini crowd, and is also possibly the best choice on this list to wash down a raw bar platter of oysters. Those pristine mollusks are even better followed by a crunchy, boozy onion chaser.

— Craig LaBan

Gibson, $15, Royal Boucherie, 52 S. Second St., 267-606-6313;