I'm not sure what Grandma uses, though I'd assume lard. She doesn't cook them as much anymore. What I do know is that Dad used to trade his bean tacos for chorizo/egg when they worked in the fields because the other pickers knew that Grandma made the best flour tortillas. Dad would trade up, haha!
I used shortening because that was what was recommended to me. I also just used my hands because I wanted to make sure the texture was right. It all worked out and they were flexible and delicious. Part of me wants to make the "sweet" tortillas my sister makes, so I'm going to try that later. They are just a hint sweeter than the ones I made and are meant to be eaten plain. Mmmm, I can't wait to try it out. I'll have to make a new batch of normal tortillas, though. Nobody else seems to like the sweet ones, hmph.