Here are a few vegetarian restaurants in Manhattan that I've found worth the visit. Hangawi is a rather upmarket Korean restaurant serving only vegetarian food. The 'Emperor's Feast' is $35/person, but worth every penny (sorry, cent). The Chennai Garden is a vegetarian Indian restaurant specialising in South Indian food. I've taken numerous non-veggies there and no-one has ever complained. Good value for money, too.

Candle Cafe is a mostly vegan bistro on the Upper East Side. Very reasonably priced, although it can get crowded. Great veggie burgers and sandwiches.