1 1/2 cups masarepa (Corn meal)
1 1/2 cups water, plus more as necessary
1 teaspoon vegetable oil
2 teaspoons butter
Fillings as desired, such as cheese, beans, shredded chicken, or Pulled Pork
Adjust oven rack to middle position and preheat oven to 325°F. Combine masarepa, cheese (if using), 1 cup water, and 1 teaspoon vegetable oil in a medium bowl and knead with hands until a dough is formed. Take a small amount and flatten it between your palms If the edges crack, knead in more water a tablespoon at a time until dough is supple and smooth but not sticky. Season dough to taste with salt, then cover and set aside for five minutes.
Divide dough into four even pieces and roll into balls. Working on a wooden cutting board or a regular cutting board with a sheet of plastic wrap or parchment paper on top of it, flatten each ball down to a disk about 4-inches in diameter and 1/2-inch thick.
Melt butter in a 12-inch cast iron or non-stick skillet over medium-low heat (see note #3 above). Add arepas and cook, moving them around the pan and rotating them occasionally, until first side is charred in spots and a dry crust has formed, about five minutes. Flip arepas and cook on second side until a dry crust has formed, about five minutes longer. Transfer to a baking sheet and bake until cooked through, about 10 minutes longer. Remove from oven, let rt 5 minutes, split, fill, and serve.