My wife has celiac’s, and our other friend has an intolerance, so we are always conscious of this.
Condado Tacos and Emporio were both excellent at labeling, and we’ve eaten there multiple times.
Burgatory (multiple locations, but one across the way by the stadiums) is also excellent at labeling what is safe, plus they do a gluten-free bun.
At Ten Penny (a few years ago now), their labeling wasn’t very good, and my friend indicated that he needed to avoid gluten. They literally put his meal on a bed of bread, so we haven’t been back there since.
My wife loves the FindMeGlutenFree app for traveling, so we recommend that as well if the above isn’t to your liking.