When I moved to Arizona from Colorado I thought there was bound to be better Mexican food options than Colorado. There were a handful of Mexican restaurants that really impressed and did not seem like the TexMex you come to expect. Carolina's is the top of that handful of restaurants.
It gets packed quick at lunch time and often times you have to send someone to hover over tables while others in your party order food. It makes for a weird atmosphere, but the food has always been good.
I no longer live in Arizona, but this and a few other restaurants are on my list to try and make sure I make it to when I travel back there.