Combine flour, baking powder, and salt together in a large bowl. Cut in shortening by hand, or with a pastry cutter until mixture is crumbly. If mixture looks more floury than crumbly, add one or two more tablespoons of shortening. Add about 3/4 cup hot water, or just enough to moisten.

Knead dough by hand or with a large fork, rubbing dough against the sides of the mixing bowl to gather any clinging dough. If dough still sticks to the side of the bowl, add a couple more tablespoons of flour until dough forms a soft round shape. For best results, cover dough with a clean dish towel, and let it rest for about an hour or so.

Divide dough into 12 equal-sized balls. Roll each ball on a lightly floured surface to about 1/8-inch thick.

Heat a cast iron skillet over medium heat.

Place a tortilla in the preheated pan and cook until browned and slightly puffy, about 30 seconds to 1 minute. Turn tortilla over to brown on second side, about 30 seconds or a minute more; transfer to a plate. Repeat with each piece of dough. Keep cooked tortillas covered with a towel to stay warm and moist until ready to serve.