When I started NSD, I tried to remain vegetarian but after speaking with Professor Ebringer I resolved to resume eating meats after 22 years! It was a difficult transition, but vegetarian/vegan is not compatible with AS!
Now that I have no active disease, but developed gout (perhaps due to long-term AS-related kidney issues), I have become vegetarian once again. The foods I like are mostly vegetables, properly prepared with a little hard cheese sometimes. Tofu is good, nuts (except obvious ones like legume peanuts and especially cashews), halvah, coconut, raisins, properly tested fruits, etc. There are many options, but it is difficult even still to find the variety we need.
I have been working on a protocol--some suggestions--for AS guys in India--which is worst-case as far as diet is concerned.