You can get steak anywhere. I suggest you find somewhere that offers cabrito, and order that instead. You just may discover a new favorite meat dish. I can't remember the places on River Walk that had it last time I was there (six years ago) but look at menus online.
Hard to beat the Mexican food in San Antonio. Most of the really good stuff is in the off the beaten path Mom & Pop joints, though. Not on the River Walk.
If I want a damn good steak, I’ll grill it myself over a mesquite fire.