Place the flour and salt in a medium bowl and stir together. Next cut the fat (butter or butter and lard) into small-ish cubes or slices  and add to the bowl.Using a pastry cutter or two forks cut the fat into the flour and salt until it is crumbly and almost looks like sand with some larger pea sized chunks throughout.

Next add the sourdough starter and roughly cut into the flour and butter mixture. It doesn't have to be perfectly blended in at this point because it will mix in later.

Then slowly add the HOT water starting with a half cup.  Stir it together until thoroughly mixed (you may have to use your hands to get it all mixed well).  If it is still slightly dry keep adding hot water a little at a time. Mine usually takes about 3/4 cup total but this varies depending on your flour and the weather.

When you have a nice soft dough that is pliable but not sticky stop adding water. Cover with an air tight cover and leave to ferment for 8-12 hours.

When the fermentation period is up flour a counter and begin rolling out the tortillas.  Taking a golf ball size piece of dough place it on the floured counter and flatten it with your hand.  Place a little more flour on top and roll out until it is really thin (like ya know, tortilla thin). Set aside and continue with the rest of the dough.

When all of the dough has been rolled out preheat a 10" or 12" cast iron pan over medium-medium/high heat. Once it is hot place one tortilla on it.  Watch as it puffs up magically and when it's been on the skillet for 15-30 seconds flip it.

Cook on the other side for another 15-30 seconds.  Remove to a plate and repeat with the rest of the tortillas.

Cool completely before storing.  Can be stored at room temp in a air tight container for 3-5 days or froze for 6 months or so. Enjoy!