Combine masa harina and salt in a large mixing bowl and whisk to blend.
Add 1 cup of warm water and stir with your hand or a wooden spoon until fully absorbed. Gradually add remaining water 2 tablespoons at a time until the dough pulls together into a cohesive ball.
Knead the dough in the bowl for 2-3 minutes until it feels like soft playdough, moist but not sticky. Perform the crack test by pressing a small piece between your fingers; if edges crack significantly, add 1-2 tablespoons more water.
Cover the dough bowl with a damp kitchen towel and let it rest for 10-15 minutes.
Divide the dough into 12-16 equal portions (golf ball size, 35-40g each) and roll into smooth balls. Keep covered with a damp towel while you work.
Cut a plastic zip-top bag along the side seams to create one large sheet or cut two squares of parchment paper. Place the plastic sheet on the bottom plate of your tortilla press.
Place a dough ball in the center, flatten slightly with your hand, place the second plastic sheet on top, and close the press with firm, even pressure until the tortilla is about 6 inches in diameter and 1/8 inch thick.
Preheat your cast iron skillet, griddle, or comal over medium-high heat for 5 minutes until very hot. Test by sprinkling water drops; they should sizzle and evaporate within 2-3 seconds.
Peel the top plastic sheet, flip the tortilla onto your open hand, and lay it flat on the hot cooking surface. Peel away the remaining plastic. Cook for 30-45 seconds until edges begin to dry and small brown spots appear.
Flip the tortilla with a metal spatula and cook for 45-60 seconds until more brown spots appear. Flip back to the first side and cook for another 15-30 seconds until the tortilla puffs up.
Transfer the cooked tortilla immediately to your tortilla warmer or wrap in a clean kitchen towel. Repeat with remaining dough balls, stacking cooked tortillas to keep them soft and pliable.