If you've never had Sopapillas, you've probably had Fry Bread or Scones, which are quite similar. This is my moms tried and proven recipe that she would make for us while we were growing up.
2 cup flour
3 tsp. baking powder
1 tsp. salt
3/4 cup warm water
I generally mix the baking powder, salt and water together with 1 cup of flour, and add flour from there, and mix it in my bread mixer. It works really well that way. Then just take a golf ball size dough, roll it out super thin, and place in it some oil. It should puff up nicely, then turn it, and fry the other side. Yum! enjoy it with your dinner or as dessert with honey and powered sugar. If you want a picture, go to my Pasole recipe (look under soups).
Tip: One time, I doubled the recipe because we had company over, and I needed a little more, but I didn't end up using all the dough. So, with the leftovers the next day, I rolled out same size proportions nice and thin, and baked them on my pizza stone, like Indian Naan bread, to go with our curry, at a high temperature for about 4 min. It worked really well!! I even impressed my husband!