Birria at the unnamed taqueria in the back of the Conoco station just off I-80 in Rock Springs, Wyoming. Seriously.
Wife & I were on our way from Jackson Hole to Denver, and we stopped at this unremarkable gas station to answer Nature's call and perhaps get a snack. Luckily, the restrooms were all the way in back and took us past the small, unremarkable room with a few faded picture-menu placards and formica tables. We probably would have taken a pass, but: 1) no Anglos in sight, either behind the counter or at the tables; 2) the relish/garnish at the tables looked fresh and homemade; 3) they had menudo (it being a Sunday). The wife was severely disappointed that they had just run out of the menudo, but we consoled ourselves by splitting a birria platter, which was damn near perfect. The meat was tender with just the right level of saltiness, the tortillas may not have been homemade, but they tasted that way, and all of the fixin's were fresh and lovely. The utter improbability of it surely colored our reaction, but we both agreed it was some of the better Mexican food we'd tasted in a long time---and as a Chicago-Texas couple, we consider standards reasonably high.
So if you're ever in southwestern Wyoming, heading towards Salt Lake City or coming out of the Tetons, check it out (and tell me how the barbacoa is).