I think there may be some in SoCal as well, but not sure.
For anyone living in, or traveling to/through Las Vegas, I HIGHLY recommend it. Make sure you get the al pastor tacos. They are on another level. And make sure you ask for everything on them, including pineapple. They won't add the pineapple unless you specifically ask for it. They are the best tacos I've ever had, and it's really not close. You won't regret it.
The best location is the original in Las Vegas on East Charleston. Not the best part of town, but worth the risk. All locations are good, however.
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