I didn't try it, but unti you get other answers I'll share my experience.
I ate at Sanaa last week and it was the best meal of my trip. I had the appetizer trio, which consisted of potato & pea samosas w/a fruit salsa, roasted cauliflower that sat on a bed of tomato sauce and lamb kefta (which, of course, you wouldn't want). The food was fantastic! You can order the samosas and cauliflower as individual appetizers to avoid getting the lamb kefta.
Also, their naan (bread) was the best I've ever had. They make it fresh and each slice covers an entire plate. I could have eaten just that and been happy!
Hopefully you'll get some reviews from actual vegetarieans, but the veggie options I had were great!