Many restaurants are offering special dishes to vegan & vegetarian customers, some of them would cook for you. Bosco Verde, Luna Blanca, Loving Hut, Eco evento are offering vegetarian food, besides Namaste and Ceylonta have vegetarian options on their menu.
It is easy to find halal food since many Turkish and Indian restaurants are located in UB such as Gobi cave, Istanbul cafe, Anatolia, Namaste, Mughul, Los Bandidos and more. The meal is really tasty and filling, and the prices aren't too high. The staffs are quick and speak some basic English.