Pupusas, in case you don't know (I know I didn't) are the local, corn-based hand-pie. They're almost all savory, and really most of them are just stuffed with meat. They're also cheap--cause they use left over "meat"--and fast, 'cause most people keep some spare dough mixed up if they've got a fridge.
Or, you know, even if they don't.
Basically, you pick up some ground corn--the type for making tortillas. The ground maize here is a little finer than they use in Mexico, but it's close enough. Follow the directions for making tortillas, up through the mixing. They'll usually say to use lard, but I don't see why plain crisco wouldn't work just as well (I'm still eating without asking--I'd like to eat more than once a day and it's the only way to manage it).
Take a ball of mix, probably about what they say to use for a tortilla, a quarter cup or so, and flatten it out until you've got a disk about 5 inches across. Then do another just like it. scatter a couple tablespoons of filling over one disk, keeping it less than half an inch thick (closer to 1/4 is better) and staying about a quarter to half inch away from the edge. Place the second disk on top of the first and squoosh the edges together to seal them shut.
Then, you toss them on a hot griddle or frying pan that's been barely sprayed with oil. Cook over medium to high heat (lower if things start to burn) until the bottom starts to lightly brown and cook. Then flip and cook until both sides are cooked and the insides are warm. If you use cheese, don't be surprised if they leak a bit.
At the shops or street vendors it takes them about 10 minutes to cook them, starting from dough. Figure with a big enough pan or griddle, and someone to make the disks, you could get production going on about 100 an hour...
Of course, two is more than enough to fill even me. For a while.