You didn't mention which city, but if you're in the DFW area, Sin Fronteras in Irving has three very good versions of Ceviche. They serve it with jumbo Peruvian corn and yams.
It's been a while since I've been there, but I think they're still in business. From our experience, it's best to stay far away from their mexican food menu and just order the Peruvian dishes. They still should also be BYOB.