This recipe is adapted from the Rick Bayless book 'Authentic Mexican,' which is a book I really like. Masa harina is fine, lime-treated corn flour that you can find in the Mexican-foods section of any large supermarket or natural foods store; I use Masa Brosa brand, but only because that's what there was -- I don't have any particular brand allegiance.
To make enough only for dinner for a family of four, halve the recipe and make 8 tortillas. (Of course, if you've got time, it's better to make the full recipe and store leftovers in the fridge in a Ziploc -- but it's much quicker to make half.) Also: I want credit for another recipe with NO SALT in it.
Yields 15 tortillas
Stir together the masa harina and water, then knead it on the counter until it's smooth, adding more water or masa harina as needed to make a soft but not sticky dough. (Sometimes I just knead it around a bit in the bowl, without even dumping it out.) Cover with plastic wrap or a bowl cover, and let it rest for 30 minutes.
Check the rested dough: It should be quite soft, so that you can press it without the edges cracking, but not so sticky that you won't be able to handle the uncooked tortillas -- a bit of a trial-and-error situation, but one with low stakes, since the ingredients are inexpensive. Divide the dough into 15 balls (a fun job for a child!) and keep them covered while you work.
If you have a tortilla press, then do whatever you need to do to prepare it. If you don't, then cut a gallon-size Ziploc freezer bag into two large squares of plastic and get out a Pyrex pie plate. This will be your makeshift press -- and it will work beautifully.
Now, heat a cast iron griddle or a pair of frying pans that can stand high heat. One side of the griddle or one pan should be on high heat, and the other should be on medium-low heat.
Press the tortillas: Place a ball of dough between the two squares of plastic, then press down with the pie plate, smashing and rocking it a bit to get the tortilla nice and flat. Peel it off of the plastic carefully (peel the top plastic off first, then flip it so the tortilla is in your palm and peel off the other plastic square), then slap it onto the cooler frying pan or the cooler side of the griddle. After 30 seconds or so, the tortilla will be dry enough to move easily, and you should flip it onto the hot side of the griddle (or the hotter pan), where you'll cook it until it's browning in spots before flipping it and browning the first side. Did you follow that? Side A down on cooler griddle; flip to side B down on hot griddle; flip to side A down again on hot griddle. Rick Bayless says this should be about 30 seconds a side, but I end up leaving mine on the hot griddle for about a minute a side: you want them to really start to brown and to puff up a little like a pita bread. It's quite a lovely experience once you get the hang of it.
Speaking of getting the hang of it, there's a rhythm that will develop naturally once your confidence grows: you will press a tortilla and lay it on the cooler part of the griddle; you will press another and flip the first tortilla onto the hotter part of the griddle and lay the new one on the cooler side; you will press another tortilla and flip the first one on the hot side, flip the second one onto the hot side, and lay the third one down on the cooler side, etc. Following?
Keep the finished tortillas wrapped in a dish towel until you're ready to eat them. I find they can actually hold this way for a couple of hours, but if you need to reheat them, you can wrap the tortillas and their dish towel in foil and heat them in a very low oven for a while. To reheat refrigerated homemade or store-bought tortillas, wrap them in a clean, heavy dish towel and place in a steamer basket over 1/2 inch of water, then bring to a boil, covered, over medium-high heat. Steam for 1 minute, then remove from the fire and let stand 15 or 20 additional minutes.