1/2 C cooked white beans
1/2 C lukewarm water
1 T corn oil
1 t salt
1-1/4 C masa harina

In a food processor, puree the beans, water, and oil. Add the salt, then slowly add the cornmeal and process until a dough forms. Put this into a bowl and let it rest, covered, for 30 minutes.

To make pupusas, use wet hands to scoop up about 2 T of dough and flatten it to a disk, about 3 inches across. In the center, put about a teaspoon of filling — grated cheese and onions, or chopped bananas with chili oil. Then fold the edges up all the way around the filling to cover it, and flatten the whole thing with your hands to make a 4-inch filled disk.

Cook the pupusas in an oiled skillet, about 3 minutes on the first side (the seam side) and 2 minutes on the second side.