I did a search to see if this place was mentioned, but didn't see anything, so I thought I'd recommend it to everyone.
It's a tiny place on Bromfield St. near Downtown Crossing, next to Silvertone. Although it has "Mexican" in the name, I believe it's owned by a Salvadoran family. The food is excellent. The menu has the usual burritos, chimichangas, Quesadillas, empanadas, etc., but also has some special plates like grilled chicken plate and steak plate.
Everything my friends and I had was delicious. The food is made with really fresh ingredients. I had a grilled chicken plate, with a big grilled chicken breast that was moist and tender, covered with salsa fresca, and served with black beans and rice, tortillas, and a big bag of nacho chips.
My friend had the beef taco salad, which came in a shell piled high with huge chunks of marinated beef, a big scoop of guacomole, the salsa fresca, lettuce, beans and sour cream. He's been raving about it since we went.
They also have a condiment bar with the salsa fresca, along with three other kinds of salsa; a chipotle, a green salsa, and a red salsa. Each of them was delicious, with a real spicy kick to it.
It's just open for breakfast and lunch, but if you work in the area, and you like Mexican, it's definitely worth checking out.