If you want to make Pupusas (El Salvador's national dish, you're going to need some curtido. You eat pupusas with curtido and salsa roja (red sauce). Curtido is this lacto-fermented cabbage slaw/salad (Canning Cabbage Recipes)
This spicy Salvadoreno coleslaw is the traditional zesty topping for pupusas (thick corn tortillas stuffed with cheese). You can also try serving it with fish or black beans, inside burritos or on top of quesadillas.