Combine masa harina and water in a large bowl and mix until a ball forms. If it’s sticky, add more masa. If it’s crumbly, add more water.
Knead the dough for 4 to 5 minutes. You can’t overwork it!
Heat a clean, dry skillet over medium high heat.
Take a small, ping pong ball sized piece of dough from the larger dough ball, roll and flatten with your hands. If you have a tortilla press, use as directed. If you don’t have a press, get a piece of wax paper and position the dough ball on it and fold the other half of the piece of wax paper over the top, so that the dough is covered on top and bottom.
Roll out into a circular shape with a rolling pin until desired thickness. It should be thin but still opaque when held up.
Place the pressed tortilla into the heated skillet/pan and cook 45 to 60 seconds per side. It should release steam from the tortilla and cause it to puff up, but not burn.
If you are doing tacos, keep them covered with a towel to keep them moist and warm.