Place the masa in a large bowl. Pour the warm water over the masa. Mix with your hands until it comes together into a ball. Cover with plastic wrap and let rest for 30 minutes.
Cut a heavy zip lock bag in two – small enough so that it will fit nicely between your tortilla press. When you are ready to make the tortillas, place one heavy skillet over medium low heat and another heavy skillet over medium high heat.
Pinch of a piece of dough and roll into a ball about 1 1/2 to 2 inches in diameter. Lay one sheet of the heavy plastic wrap on the press. Place the tortilla ball in the center and flatten slightly with your hand. Cover with remaining sheet of prepared plastic and lay the press over the top. After your first press, open and rotate the tortilla in the plastic 45 degrees. Continue to press and rotate until the tortilla is about the size of the press and about 1/16" thick. Peel the top layer of plastic off and invert onto your hand. If your tortilla does not come away from the plastic without tearing, then it is too wet and you will need to add a small amount of masa to the dough. If the tortilla crumbles then you need to add a little water to the dough. You do not need to let the dough rest after making your adjustments.
Peel the remaining sheet of plastic off and place in the skillet over medium-low heat. Cook for about 30 seconds or until the tortilla releases from the skillet. Invert onto the hotter skillet and cook for about 30 seconds – 1 minute or until lightly browned. Invert and cook until remaining side is nicely browned in spots. Serve immediately or store for future use.
You will need a tortilla press or a heavy skillet to shape the tortillas.