Agree with al and diving cowgirl. Best real charcoal grilled chicken with rice & beans is at the square. I've also had really good burgers, taco's and burritto's there. Note: most restraunts close around 9 pm, but you can find food at the square until the bars close; depending on the weather of course and the number of people in town.
Additional favorites:
Estel's - on the beach next to the square
el fogon: //ambergriscaye.com/elfogon/