How to Make It
Weigh or lightly spoon masa harina into dry measuring cups; level with a knife. Combine masa and 1 1/2 cups water in a large bowl; stir until dough forms. Knead into a ball. (Dough should be moist enough to easily form a ball but not stick to hands.) To test consistency, break off a small chunk of dough; roll between palms into a small ball. Flatten small dough ball into a 1/2-inch-thick disk. If dough cracks around edges, add water, 1 tablespoon at a time, to whole dough batch until moist enough to press without cracking. Place a damp towel over dough in bowl.
Heat a large nonstick skillet over medium heat. On an adjacent burner, heat a large cast-iron skillet over medium-high heat.
Cover bottom of tortilla press with 7-inch square sheet of wax paper or parchment paper. Roll a 1 1/2-ounce portion of dough between palms to form a ball. Press dough ball gently to form a 1/2-inch-thick disk. Place disk on paper on bottom of press. Cover disk with another square of paper. Close press, applying moderate pressure to flatten dough ball into a 5 1/2- to 6-inch tortilla.
Remove paper from both sides of tortilla. Immediately place tortilla in nonstick skillet; cook 20 seconds on one side. Remove with a spatula. Immediately flip uncooked side onto cast-iron skillet; cook 10 seconds. Flip; cook 10 seconds. Flip; cook 10 seconds or until both sides of tortilla are lightly charred in spots. Nestle hot tortilla in a clean kitchen towel set inside a large Dutch oven or bowl; cover pan to keep warm. Repeat procedure with remaining dough (use fresh sheets of paper as needed) to form 12 tortillas total.