Let me preface this review with the statement that I am a typical St. Louis "place snob". That is, I think where I live is the best part of the area. Further, I hate St. Charles, especially since they rejected Metrolink. However, I dragged my eating group out there to try to find decent Mexican food. We found it (sort of).
El Mariachi is in a strip mall on Zumbehl road. The atmosphere is more friendly than that statement would suggest. Service was very prompt and efficient. Prices are decent and children would be welcome here. Bathrooms were appropriately clean.
Cocktails are available. Sadly, wine list was lacking - only white zinfandel was available.
We started with a serving of ceviche (spelled "seviche" at ElMariachi), which is shrimp "cooked" in lemon juice and marinated further with chopped tomatoes, onions, cilantro and fresh jalapeno peppers. This is one of my favorite Mexican dishes and El Mariachi did a darn good job with it. It was the best ceviche I've had in St. Louis. We were also served somewhat disappointing chips and terrible salsa.
One eater ordered a pork roast that he said was pretty tasty. It came with standard rice, beans, and shredded lettuce, but nothing unusual or exciting. Another person had the combo with enchilada, taco and chalupa. She said the taco and chalupa were good, but the enchilada could have used more flavor - it was somewhat bland. Another diner had a grilled chicken dish with onions and cheese on a tortilla shell with rice, beans and salad. He enjoyed it, but gave it no particular accolades.
I had the mixed fajitas, which were a revelation. A very generous amount of shredded beef, chicken and shrimp was seasoned deliciously and served up hot with all the traditional accoutrements - tortillas, sour cream, guacamole, and shredded lettuce. Curiously, no cheese was served with this dish. One diner referred to the fajitas as a tasty mess. It really was excellent.
I would return to El Mariachi for the ceviche and the fajitas. On our way out, we saw some young men who appeared to be regulars. They were eating big, tomatoey bowls of shrimp. I don't know what it was, but I sure would like to return to El Mariachi to find out.