Gluten, a protein found in grains, gives dough its elasticity, retains moisture in baked goods and makes breads pliable. Gluten plays such an important part in bread making, the term "gluten-free bread" sounds like an oxymoron. However, certain food additives, known as hydrocolloids, mimic the properties of gluten and allow you to use nonwheat flours to make breads, such as flour tortillas. When added to a standard tortilla dough made with rice flour, two of these additives -- tapioca starch and xanthan gum -- act as gluten replacements, and allow you to make rice flour tortillas that feel and taste like wheat flour tortillas.
Pour a rice flour tortilla base in a mixing bowl. A 3-to-1 ratio of rice flour to tapioca starch comprises a rice flour tortilla base. For example, if you want to make about 24 rice flour tortillas, you would use a base of 3 cups of rice flour and 1 cup of tapioca starch.
Add xanthan gum to the base ingredients. You need about 1 teaspoon of xanthan gum for every 2 cups of rice flour tortilla base. So for 24 rice flour tortillas, you need 4 cups of rice flour tortilla base -- 3 cups of rice flour and 1 cup of tapioca starch -- and 2 teaspoons of xanthan gum.
Add a pinch of baking powder and a pinch of salt to the dry ingredients. Add granulated sugar to the dry ingredients to taste. Unlike yeast breads, the sugar in tortillas is only for taste and not to feed the yeast, so you can use as little or as much as you like. If you're unsure of how much to use, a pinch or two of sugar usually does the trick.
Whisk together the dry ingredients with a balloon whisk. Balloon whisks are made for mixing batters or dry ingredients. Their bulbous shape distributes and disperses ingredients efficiently, they fit almost perfectly against the sides of a mixing bowl and their tines are spaced to breaks up clumps. If you don't have a balloon whisk, you can get by with a regular French whisk if you mix diligently.
Cut the shortening into 3/4- to 1-inch cubes. You need about 1 tablespoon of vegetable shortening for every cup of rice tortilla base. For example, if you're making 24 rice flour tortillas, you need 4 cups of tortilla base and 4 tablespoons of vegetable shortening.
Drop the cubed shortening into the dry ingredients. Pick up each cube of shortening and toss it in the dry ingredients, completely coating each piece.
Cut the shortening into the dry ingredients using a pastry blender or the back of a fork until the mixture reaches a crumbly consistency and looks like coarse meal.
Pour cold water in the mixing bowl. You need a 4-to1-ratio of tortilla base to water. So for 24 tortillas, you need 4 cups of base and 1 cup of cold water.
Stir the dough together with a wooden spoon until incorporated. Continue stirring while pouring just enough water for the dough to stick together and pull away from the sides of the bowl. The dough should feel tacky, but not stick to your fingers, and it should be moist, but not loose. If needed, add a touch of water or a pinch of flour to achieve the proper consistency.
Turn the dough out onto a rice-floured work surface. Knead the dough for about three or four minutes. Lightly dust your hands with rice flour if the dough sticks.
Place a comal or a 12-inch cast iron skillet on the stove on a burner of about the same size. Set the heat to medium-high.
Wrap both sides of a 10-inch tortilla press with plastic food film. Lightly dust both sides of the tortilla press with rice flour.
Pinch off a couple tablespoons of tortilla dough, and into a tight ball between your palms, like you were rolling a meatball. Place the dough in the center of the press. Close the tortilla press on the dough and open it. Peel the tortilla from it and lay it on the comal or in the skillet.
Cook the tortilla until it doesn't feel doughy and turns golden-brown in spots, about 1 to 1 1/2 minutes on each side. Turn the tortilla over by hand or with a spatula when needed. If the tortillas start to puff up, poke the bubbles with a toothpick or skewer.
Cover the tortillas with a towel after you take them off the comal to keep them warm and moist.