Add the masa and sea salt to a large bowl, and then pour 2 1/4 cups boiling water over it.
Use a wooden spoon to mix together, and when it's cooled enough, use your hands to begin kneading the dough.
For the softest and most pliable tortillas, continue to knead for 4-5 minutes, although this step is totally optional. I usually don't do it.
As I knead the dough, I add a tablespoon of water when it starts to crack, and it brings it back together.
Allow the dough to rest for 15-30 minutes, to allow the water to fully soak into the corn flour.
Separate the dough into 2 portions, and then separate both of those balls into halves, until you have 18 small balls.
Roll each section of dough into a smooth ball. Wet hands to smooth the ball if it is cracking.
Use a tortilla press to flatten, or read the tips above for the method I use, no press needed!
Preheat a skillet over high heat, and then cook each tortilla until browned spots appear, flip, and cook for another 30 seconds.
Remove from heat, and keep wrapped in a towel until read to serve.
Unused tortillas can be kept in a sealed plastic bag or container in the fridge. Reheat in a skillet to soften again.