Shangri-La is the best vegetarian (Buddhist) Chinese restaurant I have ever been to: cheap, tasty, inventive, and authentic (they are associated with a local Buddhist monastery -- monks often are in the restaurant at lunch time).
They used to have only a few "fake meat" items, but caved a few years ago. I prefer the original menu items. Try the cold tofu and hot cucumber appetizers. The hot-and-sour soup can't be beat. My favorite main dishes are hot-sauce broccoli, hot-sauce eggplant, and vegetables with gluten. Sweet-and-sour walnuts are a fabulous addition if you are getting a mix of items. If you are visiting SF, this is a "must try" restaurant.