In a medium bowl, whisk together the flour, baking powder, and salt. If using butter, work it into the flour with your fingers until the mixture looks like wet sand.
Pour in the hot water. If using vegetable oil instead of butter, add it at this step.
Stir with a fork until the wet and dry ingredients come together and a dough begins to form.
Transfer the dough to a lightly floured surface and knead briefly until smooth. If the dough feels sticky, add a small amount of flour as needed.
Divide the dough into 4 or 5 equal pieces and roll each piece into a ball.
Cover the dough balls with a towel and let them rest for about 30 minutes before rolling.
Heat a cast iron or nonstick skillet over medium heat until hot.
On a lightly floured surface, roll one dough ball into an 8 inch round. The shape does not need to be perfectly round.
Place the rolled dough onto the hot skillet. Cook for about 40 seconds, until bubbles form on the surface and golden brown spots appear on the bottom.
Flip the tortilla and cook until golden brown spots form on the second side. Transfer to a plate and cover with a clean towel to keep warm. Repeat with the remaining dough.
Notes
Fat Choices: This flour tortilla recipe works with butter, vegetable oil, or lard. Add oil with the hot water. If using butter or lard, work it into the flour before adding the liquid.
Baking Powder: Baking powder is optional. Leaving it out will produce tortillas that are slightly flatter but still soft and flexible.
Rest the Dough: Letting the dough rest relaxes the gluten and makes it easier to roll. If the dough springs back while rolling, let it rest for another 10 minutes.
Roll to Your Preference: Roll the dough thin for soft, pliable tortillas. Slightly thicker tortillas are sturdier and work well for wraps or flatbread-style uses.
Adjust the Size: Divide the dough into more or fewer pieces to make smaller taco-size tortillas or larger burrito-size tortillas.
Heat Control: Keep the skillet at medium heat. If the tortillas brown too quickly or turn stiff, lower the heat slightly.