In regular restaurants, there is very little offered to vegetarians, and even especially vegans. However, if you’re rather strict about not wanting your foods to be contaminate with meat or other animal products in the process, then there are a few 100% vegetarian/vegan, animal-free restaurants.
The one I usually go to in San Diego is… Sipz.

If you just check out their website there… there’s one in Clairemont. Its branch is in the Sorrento Valley Foodcourt.
Other restaurants… this is a vegan restaurant franchise. Loving Hut.
Although there is none in San Diego. Check out their website if you live in LA, San Fran, and San Jose.
I haven’t really gone to any other 100% animal-free restaurant that is worth recommending yet. I’ll be sure to update.