Mix the corn or rice flour with water by hand in a bowl until it forms a soft dough ball.
In a separate bowl, mix together cheese and cooked ground pork mixture. Set aside.
Using about 3 tablespoons of mixture at a time, form a ball in the palm of your hands (like making meatballs.) Place half a tablespoon of the filling in the center of the dough ball and fold the edges around the filling, shaping the dough into a ¼ inch thick disk with the fillings hidden inside.
Put the dough disk in a pre-heated non-stick frying pan (for crispier pupusas, grease the pan with 1 teaspoon of canola oil).
Cook for approximately 1 1/2 minutes on each side, until golden brown. Serve warm.