El Guapito - Ample and Delicious Mexican in Downtown Baltimore - 111 W. Mulberry
The restaurant formerly known as El Torito.
OMG - go! The tacos carnitas, de lengua and al pastor are outrageous. $2.75 each. Add a side of beans or rice and walk out as stuffed as their chile rellenos.
There's already a thread raving about this place, but it's under the former name (changed because of trademark issues, but same owners)
eta: the address is 110 W. Mulberry, not 111 W. Mulberry. It's on the north side of the street.