In a mixing bowl, combine the flour, salt and vegetable shortening with your hands, slowly incorporate the lukewarm water and mix until it can come together into a ball. Transfer to the counter and knead for about 2 to 4 minutes, until it is smooth like play dough.
Divide the dough into halves until you have 16 balls of dough. Place them on a floured sheet or board, cover with a clean kitchen towel and let them rest for 25 to 35 minutes.
Heat your comal or ungreased cast iron or non-stick skillet over low heat. On a lightly floured surface, roll out each ball with a floured rolling pin, rotating 5 or 6 times until you get a 7” round.
Place the tortilla on the already heated comal or skillet. You will hear a faint sizzle. After 40 to 50 seconds, when there are brown freckles on the bottom side and there are air bubbles puffed up all over the tortilla, flip over. Cook for 40 to 50 seconds more, until the other side is freckled and the tortilla puffs up even more, like pita bread.