Salvadoran Bean-and-Cheese Pupusas with Curtido

Prepare the vegetables by finely shredding 3 cups cabbage, coarsely grating 1/2 cup carrot, and thinly slicing 1/2 cup onion. Finely shred the mozzarella if needed.

Combine the cabbage, carrot, onion, sugar, oregano, and half the salt in a bowl. Massage firmly for 2 minutes until the cabbage begins to soften. Add the vinegar, toss well, and let the curtido stand for 25 minutes, tossing once halfway through.

In a second bowl, stir together the refried beans and mozzarella until evenly combined. Divide into equal portions, allowing two pupusas per serving, and keep covered.

Combine the masa harina and remaining salt in a large bowl. Add the warm water and mix by hand for about 1 minute. Knead until smooth and pliable, with a texture like soft modeling clay, then rest the dough for 5 minutes under a damp kitchen towel.

Heat a large skillet over medium heat for 3 minutes. Add one-third of the vegetable oil and spread it into a thin film.

Cook without crowding the skillet, using the oil already added for the first batch and spreading a little of the remaining oil into the skillet between batches. Allow about three batches at the base serving size; larger batches of dough need more skillet batches. Cook for 4 to 6 minutes per side until browned in spots, with cooked masa and hot, melted filling. Lower the heat if the surfaces brown before the centers cook through. Do not press the pupusas as they cook.