It ain't easy, lol. Mythos is wonderful. They are happy to leave out the shrimp, etc.
Unfortunately two of the best veggie restaurants, Confisco's and Thundering falls Terrace are closed due to the slow down.
Enchanted Tavern has great side dishes, mostly carbs, cornbread, corn on the cob, etc.
The monster cafe has pasta with bread sticks (but it's pretty gross).
The Hard Rock cafe (accessible from inside Universal as well as outside) had some vegetarian items too but I haven't eaten there.