If you're in the mood for some great margaritas head over to Lauriol Plaza on 18th St.  Lauriol Plaza has a ton of outdoor seating both on the street, and on a rooftop balcony and serves up some great enchiladas, and tacos.  The dishes are very large, and filling so you can definitely share a plate between two people, especially as they provide you with free chips and salsa.  For a treat get one of the speciality margaritas - the frozen mango rita is a great deal.  They also offer pitchers if you're with a group.