The Salvadoreño storekeeper across the street has been teaching me how to make pupusas. Here's the recipe I've learned from him:
Go to your friendly neighborhood carneceria and ask 'em for some
chicharron. Make sure you don't get the chicharron that's just pork rinds; tell 'em you want it for making pupusas -- the chicharron you want is the skin, the fat, and then a bit of the meat underneath. Some stores will sell it to you as a slab, and some will sell it to you already ground.
If you get the slab, you need to soak it overnight in a solution of brine and vinegar, and then grind or shred it up to about the consistency of
snuff tobacco. The ground version may be a bit dry; if this is the case, add a little bit of water and heat the mixture up and stir until it's all a bit pasty.
Mix up a batch of
masa, making sure it's moist. Take into your hand a glob about the size of a
ping pong ball and begin patting it out into an oblong shape, rather like a long
pancake. Be careful not to pat the masa too thin; it should just cover your palm and a bit up your fingers.
Now, put a dab of the ground chicharron into the middle of the masa and fold the edges around it, sealing them by pinching. Next, pat the ball (which, after folding, looks kind of like a
gyoza) back into a flattened, round shape. This takes some practice and if the masa is insufficiently moist then the edges are likely to crack.
Cook the pupusa on a flat surface such as a griddle or skillet, but don't use any oil. The fat in the chicharron will seep into the masa and provide all the oil you need.
Top the pupusa with a spicy pickled vegetable mix (consisting of cabbage, peppers, onions, carrots, vinegar, and just enough shredded beet to make it all red).