Before I travel (anywhere) I check out the World Guide to Vegetarianism:
A few years ago when I was in NYC I went to a wonderful place called
104 Lexington Avenue
(between 27th & 28th Streets),
South Indian kosher. No additives. They had a large vegetarian menu.
Breads are whole wheat. Vegan options.
Your husband should probably try to eat in Manhattan because Queens
(especially near La Guardia) will be difficult for any vegetarian/vegan.