With greetings like " buona sera " and " come stai " flitting around, you can be assured of the honest and authentic nature of this Italian trattoria. By virtue of its location on spirited 39th Street, Mercato sees a torrent of visitors, yet it never fails to deliver a delicious blend of experiences. Most everybody here wears a sunny disposition, perhaps in response to such retro decorative touches as antique farm tools, muted walls, and vintage posters. Over in a dimly lit corner, wooden tables are filled with eager diners awaiting gifts from the kitchen including an amuse of luscious lentils; tender fried artichokes with a pat of mashed anchovy; handmade gnocchi with a thick wild boar ragù; and a beautiful red snapper encased in a semolina-polenta crust.