Add the water, tallow, and butter to a pot and heat on medium. When the fats have melted, about 3-4 minutes, turn off the heat.
Stir into the pot the flour, baking powder, and salt. Stir until a smooth dough has formed, adding more flour if needed.
Cover the dough and let it rest for an hour before rolling.
After an hour, divide the dough into 12 balls. Lightly flour a clean surface and one at a time place a dough ball on the floured surface, pat it out into a 4-inch circle, and then roll with a rolling pin from the center until it’s thin and about 8 inches in diameter.
Keep the rolled-out tortillas covered until ready to cook.
In a dry cast-iron skillet heated on medium-high, cook for 30 seconds on one side, flip it, and then cook for 1 minute on the other side. It should start to puff a bit. Flip it again and cook for 30 more seconds. Place cooked tortillas in a basket lined with cloth or a tortilla warmer. Repeat the process for the remaining balls of dough.
These will keep refrigerated for 1 week.
Notes
Beef tallow can be purchased pre-rendered in Texas at Whole Foods and usually wherever Epic Provisions products are found. Farmers market stands that sell beef will often have it, too. If you wish to render your own, you can follow the method I use for lard.