This recipe is very close to the one in Mark Bittman's, "How to Cook Everything". These are my go-to tortillas, very easy to make with a food processor. If you don't have one make them similar to biscuits, cut in the fat with a pastry knife or two butter knives and slowly add the water until dough holds together. Either way you make them make sure you don't over roll the dough when making the tortillas--they will be tough.
Add flour and salt to processor and pulse a few times to mix. While machine is running slowly add in oil, then stop processor. Add shortening and pulse a few times until it's evenly distributed (but not completely mixed) into the dough. Slowly add water, about two tablespoons at a time, just until the dough holds together. Don't worry if you still have water left over, you don't want your dough too wet.
Turn dough onto lightly floured surface and knead for a minute or two, just until the ball is elastic and smooth. Separate into 2 dough balls and wrap in plastic wrap. Set on the counter for at least 30 minutes, up to six hours if wanted. The longer it rests the easier it will be to roll out. I'll sometimes pre-heat my oven to it's lowest setting, turn it off, and let the dough sit in there for 30 min if I don't have a lot of time.
When ready to start rolling heat up a large frying pan (preferabbly cast iron) to medium-low to medium. Unwrap one dough ball long enough to pinch off about 1/7th of the dough. On LIGHTLY floured surface roll out tortilla until it is very thin, about 7 inches in diameter. I can never roll in a circle so mine generally look like a map of the US. Do NOT over-roll.
When pan is heated place tortilla inside. You'll start to see bubbles, and possibly some shrinkage. Wait until the edges are set and and underside is done, about 30-45 seconds. Flip, second side usually cooks a bit faster, 30 seconds. (For whatever reason my first tortilla is always tough. Haven't figured out why, but happens every time.) Transfer to a sheet of foil, place second sheet over the tortilla to keep from drying out. Repeat with the rest of the first dough ball, and with the second. Make sure you're ALWAYS re-wrapping your dough ball so that it doesn't dry out, and re-covering your cooked tortillas with foil to keep soft.
Store tightly covered in the pantry for a day or so. Ours never last that long, though!