Mix together masarepa, salt, and water until combined. You want your dough to be fairly wet but not too wet.
Let your dough sit for about 5-10 minutes, covered, until it is hydrated.
Divide your dough into 3 pieces and form each piece into a ball. Flatten into a disk and set aside to fry it you are not stuffing them.
If stuffing with cheese, form a well in your dough ball and fill with shredded mozzarella cheese. Pinch your cheese into your dough ball, and flatten into a disk. When I stuff my arepa I make about 4 stuffed arepas but when I am not adding anything in them, I get about 3.
Preheat your oven to 350 degrees.
Pan fry your arepas in a pan on medium heat with oil until seared on each side and light brown on each side. This is about 1-2 minutes per side. You can make them as light or as charred as you please.
Place in oven and bake for 10 minutes until slightly puffy. This step is optional but I like that they puff up slightly in the oven and get a bit more crispy on the outside. Remember you are using precooked cornmeal so it is not raw.
Serve hot on its own, sliced in half with more stuffings or with toppings right on top.