In a large mixing bowl, combine masa harina, sea salt, and water.
separate the masa into 12 equal balls.
Take one ball and flatten it into an approximately 4 inch circle in the palm of your hand.
Place 2 tablespoons of cheese into the middle of the flattened masa circle and pull the outside of the circle together to close the cheese inside.
Reflatten the pupusa to a 4 inch flattened circle.
Fry the pupusas on a hot, lightly oiled griddle for 5 minutes on each side. Continue steps 4-8 until all the pupusas are cooked. Serve immediately with curtido.