One guy elected 12 years ago for a down ballot position. Got it. What percentage of Texas is Hispanic, again?
He's not the only one, no. His successor was also Hispanic, Victor Carjullo, and won both a primary and a general in 2004. Garza was merely the first.
You specifically asked for a Hispanic that had to be elected via a primary first, which excluded many Hispanics. The Democrats, to my knowledge, have not elected any Hispanics to statewide office in Texas even when they could win in Texas. In fact, I don't know of many Hispanics that have had the success of the Texas Republican Party...certainly not, say, the California Democrats.
Texas is about 38% Hispanic of course.