The problem I have found with homemade tortillas made using only masa harina (ground corn and lime juice) is that they come out rigid and too crispy to wrap into tacos. This recipe solves that by replacing half the masa harina with all-purpose flour.
Combine the masa and flour in a bowl with the salt. Add the hot water (you might not need all of it) and knead until the dough resembles a pie crust. Wrap in plastic and refrigerate for at least 1 hour.
Preheat the oven to 300 degrees F.
To make the tortillas, press or roll golf ball-size pieces of the dough into thin tortillas using a tortilla press or rolling pin.
Heat a large skillet over medium-high heat. In batches, add some butter or oil, then saute the tortillas for 3 or 4 minutes per side. Wrap the tortillas in a dishtowel, then place in the oven to stay warm and soften slightly.