Step 1

First, make the curtido: Combine the cabbage, carrot, and onion in a large bowl. Combine the remaining ingredients in a separate bowl and then pour over the cabbage mixture and stir. Cover and refrigerate for at least 2 hours and preferably at least a day before serving.

Step 2

Make the pupusas: Combine the masa harina, salt, and water in a mixing bowl. Knead to form a smooth, moist dough with a playdough-like consistency. If the mixture is too dry, add more water, one teaspoon at a time. If the mixture is too sticky, add more masa harina, one teaspoon at a time. Cover the bowl with a clean towel and let stand for 10 minutes.

Step 3

With lightly oiled hands, form the dough into 8 balls about 2 inches in diameter. Using your thumb, make an indentation into one of the balls, forming a small cup. Fill the cup with 1 tablespoon of cheese and wrap the dough around the filling to seal it. Making sure that the filling does not leak, pat the dough back and forth between your hands to form a round disk about 1/4-inch thick. Repeat with the remaining balls.

Step 4

Heat a lightly oiled skillet over medium-high heat. Cook the pupusas for 2 to 3 minutes on each side until golden brown. Serve while still warm with curtido on the side.