1. Put flour, salt, and baking powder into a mixing bowl.
2. Mix the shortening or oil into the flour mixture until it forms pea-size balls.
3. Add the lukewarm water, a little at a time, until the dough is soft and pliable.
4. On a floured surface, knead the dough until smooth, for 1 to 2 minutes.
5. Place in a bowl, cover with a clean dish towel, and let it rest for 30 minutes.
6. Knead dough and form 8 to 10 balls.
7. Roll them out as thin and round as possible.
8. Preheat an ungreased griddle or cast-iron frying pan.
9. Cook tortillas on griddle one at a time, flipping when a bubble forms (less than a minute).
10. Put cooked tortillas in a plastic bag until ready to serve, to keep them warm and soft.