This is a little bit more of a tex-mex sort of place, but far closer to genuine Mexican than most so-called Mexican restaurants in Pittsburgh. You'll find burritos, quesadillas, enchiladas, etc. on the menu.
Prices are extremely reasonable, so make sure to go when you're good and hungry because you'll be able to get a lot for just a few books. The Special Combination is about $10 but comes with enough food for three people. I also really like getting just a plain bean burrito. At $3.50, it's a great lunch choice.
Chips and salsa come free with your meal and are usually pretty good. The salsa is sometimes a bit inconsistent, but that's what happens when a restaurant serves freshly made salsa. I'll take fresh over consistent any day.