
In a large bowl, place the masarepa and the salt. Stir to combine, then form a well in the middle.
Little by little pour the water into the well. Use your hands to mix and knead the dough lightly until all water is combined. Cover with a towel and let rest for 5 minutes.
Separate the dough into 8 sections and roll each section into a ball. Press the ball flat in your hand until about ½” thick. Press the edges with your hands so that no cracks form.
Heat 2 tbsp vegetable oil in a cast iron skillet until warm. Place four arepas in the pan, cover and heat over low-medium heat for 6 minutes. Flip, cover, and heat on the other side for about 8 minutes, or until a crust is formed on both sides.
Remove the arepas from the stove. When cooled enough to handle, use a serrated knife to slice the arepas in half. Layer the inside with mozzarella cheese. Place back in the cast iron for about 5 minutes, just until the cheese gets melty. Enjoy!