I learned this from one of my English as a Second Language students from El Salvador, and my Salvadorean husband appreciates them when I take the time.
A Pupusa is merely a stuffed tortilla, and are also made with pork (chicharron) or beans. It's served with cortido, or viniagrette cole slaw.
Cheese pupusas are my family favorite, and if the cheese leaks out and fries while the pupusa is cooking, that's even better! They take a bit a practice, but they're worth it.
Ingredients: Maseca corn flour, mozzarella cheese, and green peppers
Make the cortido by shredding the cabbage with onions and carrots, and mixing with your favorite vinegar. Set aside.
Then grate the mozzarella cheese, and chop the green pepper very fine, mix, and set aside.
Now, you're ready to make the pupusas.
First, heat up the griddle with a bit of oil, to medium high, then, you blend the Maseca with water by hand, until it's softer than Playdough, then rinse off your hands to make the tortilla (keep a bowl of water ready to rinse your hands when they become too sticky).
Start with a ball like a large meatball, then flatten it, turning it around in you hands, like a saucer, then on your palms. When the tortilla is large enough to fill with cheese mixture, put in a small amount (see picture) and close the tortilla around it. Flatten it again, turning it around and around in your hand, then fry it on both sides till a bit golden.