Put flour into a bowl. Weigh out your tapioca starch and add it to the same bowl.
Add in baking powder and salt. Give it all a stir to combine.
Using a pastry cutter, cut in the butter (or coconut oil) until you have small pea size pieces.
Make a well in the center of your mixture and pour half your water in. Mix with a spoon, use your hands when needed. Add in water a TBSP at a time until you have the right consistency. Your dough should not be sticky but should not be crumbly. You should have a ball of moist non-sticky dough when you are finished.
Place dough ball on a cutting board and cover with a wet tea towel for 30 minutes.
Heat a skillet on the stove (or an electric skillet) until super hot. When you splash water on it, it should sizzle.
Cut your dough ball in fourths, work with one fourth of the dough at a time, while keeping the rest under the wet towel to stay moist.
Take the section and make two or three equal pieces. Roll each piece into a ball and using a tortilla press lined with a Ziploc bag with the sides and zipper cut off, press each ball into an 8" tortilla. Your tortillas should be about 1/4" thick.
One at a time place each tortilla on the hot skillet cooking for about 45 seconds on each side or until each side has golden brown spots.
Place tortillas in a clean towel and wrap up as you work through the batch. Eat right away!
If you are making ahead of time in the same day, place the whole towel of tortillas in a Ziploc bag to keep them moist and to eat later that same day. Use a hot skillet to warm them back up before eating. However, if you are making them days ahead, store tortillas in a Ziploc bag in the freezer. Allow to thaw on the counter and reheat on a dry skillet before serving.