You know, most people have a misconception when it comes to Mexican food, that it's really cheesy and full of fat. It's actually not true, there are tons of recipies that are veggy friendly and don't require a lot of time and effort.
Here's a website that might help you on your venture:
http://mexicanfood.about.com/library/vegetarian/blrveg.htm There are SO many resources on the internet that will help you on your way, Hope that helps!!
Maria
P.S. Look in the Burrito's section, there are some black bean recipies that are really simple and tastey.