Long a symbol of the good life for Europeans and a secret handshake among connoisseurs stateside, bitters - potent herbal distillates drunk both to stimulate the appetite and settle the stomach - are finally trickling into the mainstream. Kick off your evening with a Campari-based Negroni or a Punt e Mes and grapefruit juice, then wind it down with a mentholated swig of Fernet Branca, and you're bound to be pegged as an insider - unless, of course, you gag on the truly bitter contents. In that case, better to ease in to the stuff with shots of equally strong but far sweeter Averna and Ramazzotti. You'll find a fair selection at any bar with the least Euro leanings, be it as casual as Caffé Vittoria (290-296 Hanover Street, Boston, 617.227.7606) or as chi-chi as Mistral (223 Columbus Avenue, Boston, 617.867.9300).
