Note: Bombay Chaat House and India Chaat House merged again. The food is soooo delicious and though it does take a while, the staff is very friendly and authentic and the food is always steaming and flavorful.
I've gotten a couple of things there, and it was all wonderful, but the last time I went, I was still vegetarian, not vegan. I'm sure that they have some vegan options or could make some adjustments to accommodate a vegan customer, but the staff doesn't speak English very well, so it might be difficult to ask. I'm sure they get that kind of question a lot though, and would be totally willing to help. They're really great.
It's kind of out of the way, not with the rest of the food carts at all, but definitely worth the walk and definitely worth the wait.
Cons: hard to find, not much seating, long wait