Probably the best Mexican fast-casual restaurant I have found so far in Phoenix. I too think the carne asada tortas (steak sandwich) are great. I also recommend ordering a torta with the refried beans in the sandwich.
They also have great soft tacos with carne asada or marinated pork. You will also find a few exotic plates like lengua (tongue) and barbacoa (beef from the cow's head).
Other pluses ... the two sisters that run the place are absolutely gorgeous. And it has a great atmosphere with Latin music playing in the background (not too loud either).
They will be featured on the Food Network in Diners, Drive-ins and Dives this upcoming season.
The only complaint I have is that their chile rellenos are average at best. Not a five star, but I have yet to rate a Mexican restaurant five stars in the Phoenix area.