Although most restaurants had vegetarian items, they were almost always covered up in cheese. One nice surprise was a Mexican place called Rose's Cantina. The waitress was extremely helpful, going so far as to have the kitchen make us a special batch of guacamole without sour cream (as if sour cream ever belonged in guac anyway). She helped us figure out what on the menu would be easily adapted, and made an excellent suggestion for adding an ingredient to the dish that we chose that we didn't know was available. By far the most pleasant dining experience we had.
In contrast, we went to local Austin chain Iron Cactus Monday night... I have to say I was surprised to be informed that they were unable to make as simple a change to a menu item as making some enchiladas without cheese in them. Apparently the dishes are all prepared ahead of time, and there was no one in the kitchen capable of cooking something from fresh ingredients. Sad. So I ended up with veggie fajitas - again. They were good, don't get me wrong. I've just come to expect better from a place that has the gall to charge $9 for tableside guac.