Last month chef Michael White and his business partner Chris Cannon opened Convivio in the space formerly occupied by L'Impero, which White took over after the abrupt departure of chef Scott Conant (who has since opened Scarpetta). Where L'Impero was perceived by some as stuffy and overly formal (Times critic Frank Bruni said it evoked "the upholstered interior of a very large coffin"), Convivio aims for a more casual, though still elegant, atmosphere, with "burnt......