Add 4 cups of masa to a clean bowl.
Add 3 cups of warm water.
Add one teaspoon of nor de poyo.
Let the mixture sit for five minutes without touching it.
Mush everything all together with your hands for about five to six minutes until it turns into a nice ball.
Remove the dough from the bowl and put it on a flat surface.
Knead for about two to three more minutes until it has a Play-Doh consistency.
To check consistency, take out a little bit, roll it into a ball, and if there are no cracks, it's good. If there are cracks, add a little more water a little at a time.
To fill the pupusas, mash mozzarella cheese and a little bit of milk together until it has a mashed potato consistency.
Add a little bit of oil to a bowl.
Wash and clean your hands.
Put a little bit of oil on your hands.
Get a little piece of masa, make it into a little ball, and flatten it.
Make the flattened masa into a little boat.
Add some cheese inside the boat.
Close the masa around the cheese, putting any excess back into the masa.
Flatten the stuffed masa again.
Fry the pupusas until golden brown on each side, but not burnt.
