In the Southwestern United States, corn flour is known as "masa," or "dough" in Spanish. Masa is made from corn that has been soaked in lime water overnight, dried and then ground. This flour is useful for making corn tortillas, tamales, empanadas and other items in Latin cooking. Masa is readily available in the baking aisle of your grocery store; however, you can make your own masa at home if you have the correct ingredients and a little patience.
Pour 3 quarts of water into a stainless steel pot. You must use a noncorrosive pot because lime will react with some metals. Turn the burner on high and stir to dissolve the lime in the water.
Add the corn to the water and remove any corn that floats to the top because it might have gone bad. Bring the corn to a boil and then reduce the heat to medium-low. Simmer the corn for 12 to 15 minutes if you need the masa for tamales, or two minutes if you are making tortillas.
Remove the pan from heat. If you are making tamales, leave the corn to soak for one hour. If you are making tortillas, leave the corn soaking in the water overnight. Tortilla masa must be finer than masa for tamales, and the extra soaking time allows the lime to break the corn down further.
Drain the corn into a colander and wash the corn under cool water. Rub the corn between your hands to remove the hulls. Make sure that all of the hulls are removed and that only the pale white inside portion of the corn kernels are left, otherwise your tamale or tortilla will taste like lime water. Discard the hulls.
Dry the corn by pressing it between two clean towels. Then grind the corn either by using a specialized grinder, a food mill, food processor or by using a stone metate. Grind the corn very fine for masa for tortillas, or grind it coarsely for masa meant for tamales.
Use the masa to make tortillas or tamales immediately, or refrigerate it for one to three days for optimal freshness. If you have any leftover, wrap it well in foil and freeze it for up to one month.