In a large mixing bowl, add the Masa harina and salt. Whisk to combine. Feel free to spice up the dough by adding a pinch of garlic powder, cumin, paprika - not authentic but flavorsome.
Pour cold water over the flour and start stirring with a spatula. When it starts to be difficult to stir, knead by hand or with a stand mixer paddle attachment for 1 or 2 minutes until the dough resembles a clay-like texture. The dough is still slightly wet at this point - set aside 15 minutes to rest.
Slightly oil your hands to prevent the dough from sticking to your fingers. Then, scoop out 3 tablespoons of dough and roll into a ball. If you are a visual learner, watch my pictures above in the post to see how to fill and fold the Pupusa easily in the next steps.
Flatten the ball into a thick, even circle. Hold in the center of one hand and fill the center with no more than 2 teaspoons of filling - can be 1 teaspoon of refried bean and 1 teaspoon of cheese or just cheese as you like!
Close your hand to fold the dough into a pocket and pinch the sides to seal. Roll into a ball again and pat out between your hands to flatten and form a thick circle of flatbread.
If cracks show, pat some extra dough to fix the holes or smoothen with wet oily fingers.
Set aside on a plate covered with parchment paper and repeat for the leftover dough.
Warm a non-stick cast-iron skillet over medium-high heat.
Cook the Pupusas for 2-3 minutes on one side, then flip and cook for 1-2 extra minutes. The Pupusas are ready when they are golden with dark black dots and crispy.
Serve hot with guacamole, a dipping sauce of your choice like hot sauce and coleslaw.
Store the cooked Pupusa in the fridge for up to 4 days and rewarm them in a hot skillet or bread toaster. They can be frozen and thawed in the fridge the day before eating.