Mexican Food in Texas
Of course, you'll find a plethora of Mexican restaurants all across Texas. (My favorite is Tex-Mex). In Fort Worth, Joe T. Garcia's is a must. Their fajitas are great. They now have a menu. In days passed you had two choice, enchiladas or fajitas. There's a few more things available now, but take cash, they don't accept cards.
If you're in San Antonio, Mi Tierra at market square is excellent. I've always liked Casa Rio down on the Riverwalk, mainly for the atmosphere, however, the food is pretty decent.
As far as chains go, El Fenix and El Chico are pretty reliable. The El Fenix at Cooper and I-20 in Arlington is pretty outstanding and The El Chico on Hwy. 183 in Irving is pretty darn good.
During my college years at U.T. in Austin we ate at El Patio on Guadalupe quite often. It was always one of our faves and it is still in business. When in the Lone Star State you'll have no problem finding good Mexican food to eat.