Welcome back. There are great Tex-Mex breakfasts at Blancos downtown, which also has great Tex-Mex atmosphere but I've only been there for breakfasts. Last time I was there I had lunch at Taco Taco, which is supposedly great, and it was good but I failed to have the puffy taco. Judgment is still out. Acenar on the river is a wee bit precious, but I had great mole there. Rosarios on a Friday night is might lively, and the food's good. I've now exhausted my knowledge, except for Mi Tiera and that place down on the river.
Oh, and Gloria at the Pearl Brewery is outstanding, though strictly speaking it's not Tex-Mex. It makes me jealous that it's in San Antonio. It was on NPR a few weeks ago, which was pretty cool.