Combine dry ingredients; stir well. Cut in shortening with a pastry blender until mixture resembles coarse meal. Gradually stir in water, mixing well.
Shape dough into 1 1/2-inch balls, and place on a lightly floured surface. Roll each ball into a very thin circle about 6 inches in diameter.
Cook tortillas in an ungreased skillet over medium-high heat about 2 minutes on each side or until lightly browned. Pat tortillas lightly with a spatula while browning the second side if they puff during cooking. Serve hot with butter, if desired.