Kids can have the plain cheese pupusas. They are like a mix between calzones and quesadillas.
Grown ups can enjoy the pupusas with loroco (squash blossoms) or revueltas (bean, pork thingy) or de harina de arroz (special mochi-like crunchy ones).
Wash down with the eyepoppingly tart limonada - to die for.
Get the daily special plate (tipico) for a traditional dinner - very satisfying.
The prices are incredibly low given the high quality completely home made to order nature of the meal.