Tasting menus, foraged greens, rooftop gardens: the days of having to settle for salad are over for a newly empowered class of vegetarians. Although their extremist wing, the vegans, still keep to their own commissaries, vegetarians are seeing vegetal cooking coming into its own, as a generation of U.S. chefs is influenced by Michel Bras, Redzepi and other top European toques whose best work is done on produce.