For the uninitiated, a pupusa is a ball of corn-flour dough stuffed with a variety of savory ingredients, flattened into a disc, and grilled until warm, smoky, and luscious. Over the past decade or so, this age-old Salvadoran delicacy has become a locally popular snack item and can be found at some four dozen outlets in the Mission alone. Balompie's pupusas are uniquely plump and supple and are available in 17 different and delectable variations. Try one of the classics, like chicharron (shredded pork) or loroco (a tangy vine blossom), or opt for the vegetariano (spinach, mushrooms, and carrots), the camaron (prawns and melted cheese), or the calzonelike Italiano (prosciutto and sweet basil). Every order comes with three classic condiments: crunchy pickled carrots, cauliflower, and jalapeños; a smoky tomato-pepper salsa roja; and curtido, a bright, citrusy kimchi of pickled cabbage, carrots, and spice. (Other location at 3801 Mission.)