I got take-out at De Siam on my bike trip from Montreal to Toronto, I.e. I was really hungry. There were plenty of vegan options, and apparently (I asked, just to be sure) they're not using fish sauce in any of them. Massamam curry with tofu and veggies is what I had and it tasted great. The portion size was big but not huge. Prices are moderate. I'd definitely eat there again.
Cons: Not super-cheap (but not expensive either)