Corn tortillas are made from a particular kind of flour called masa. A good tortilla is the first task to master in making great Mexican food, and it isn't easy. Good tortillas require time and expertise, and making them is a labor of love. The masa is tricky to get right, the consistency of the dough must be just so, and then there's the patting out by hand or rolling. Pressing the dough into the ideal tortilla, round and even, not too thick or too thin, takes patience and expertise. Tortillas are cooked on a round, dry, earthenware griddle called a comal.