Mix Flour, Baking Powder And Salt In A Medium Bowl. Cut In Shortening Until It Is In Pieces The Size Of Small Peas. Stir In Water And Mix Well. On A Floured Surface, Knead Dough 5 Minutes. Divide Into 12 Round Balls. Cover And Let Rest 30 Minutes. Pat Dough Balls Into Flat Round Discs And, On A Floured Surface, Roll Each Into A Very Thin 8" Circle. Bake Tortillas On A Hot Ungreased Griddle Or Cast Iron Skillet Until Brown Spots Appear, About 1 Minute On Each Side. While Cooking, Punch Down Any Air Bubbles With A Well-Protected Hand. Wrap Tortillas In A Clean Dish Towel To Keep Warm Or Freeze-Wrap In Aluminum Foil And Reheat 15 Minutes In 350 Degree Oven.