Sift together the flour and the salt, cut in the shortening until well mixed. Stir in cold water and form into a ball. Use more water if needed until the bowl is clean of all dough. Knead well in the bowl or on a floured board. Make the dough into balls the size of a large egg (makes 8).
Rub a little shortening on each ball, and let stand for 10 minutes. Pat thin, or roll out very thin with a rolling pin until the tortilla is the desired size, up to 13 inches in diameter.
Lift from board into an ungreased skillet or frying pan, on medium heat. Turn only once, allowing the tortilla to brown very lightly on each side.
The tortillas will become very slightly thicker as they cook. If they are thicker than you prefer, omit the baking soda.
2 cups flour
2 tablespoons of lard, or vegetable shortening
1 1/2 teaspoon salt
1/4 teaspoon baking soda
2/3 cup water