Even in midafternoon, this small, hip sandwich shop in the Old Port is packed. It concentrates on serving everyday farm-to-table fare here: the signature Belgian fries are made with Maine potatoes cooked, yes, in duck fat, and served in paper cones. Sandwiches are made with panini bread; choices like tuna melt with Thai chili mayo change seasonally, but the meat loaf and B.G.T. (bacon, tomato, goat cheese) are standards. Drink choices include gelato milk shakes, French-press coffee, lime-mint fountain sodas, beer, and wine.