Masa harina is a naturally gluten-free flour that is used to make masa dough. It's a very soft flour made from finely ground dried corn kernels that have been died then soaked diluted solution of calcium hydroxide (otherwise known as limewater). Soaking the flour in limewater gives corn tortillas their distinct sour flavor, while the calcium and niacin in the solution make masa harina easier to digest that regular corn meal.
Masa is the actual dough that things like corn tortillas and tamales are made from. It is a staple in traditional Mexican and Central American culture. Without it things like flautas, chimichangas, sopes, or gorditas would not exist!
Think of masa harina as the bread flour that goes into the dough of your favorite bagel! While masa harina in its powdery state does not constitute for a food supplement, it can be manipulated into the traditional Mexican and Central American foods we've grown to know and love!
Most Mexican grocery stores also sell a fresh corn masa called “masa preparada,” which is a dough made from freshly ground hominy, not masa harina flour. It can be purchased in two ways: a smooth consistency for making corn tortillas, or a coarse-textured masa with lard and seasonings for making tamales.
If you're looking to prepare your own authentic masa with masa harina, you'll should be able to find some at your local Walmart. If you strike out there, Bob's Red Mill Flour Corn Masa Harina is available on Amazon in a 4pk of 24oz bags. (More than enough for #TacoTuesday!)
Pro-tip: Smooth-ground masa should be kept well-covered at room temperature and used right away for best results. Coarse-ground masa can be covered and refrigerated for up to a week or frozen for up to three months.
There are going to be a lot of Mexican and Latin American recipes asking for masa harina because it is a staple. If you don't regularly prepare traditional Mexican dishes, you probably don't have hasa marina lying around your home, Luckily there are plenty of quality substitutes!
Most of these substitutions come from items that are already made of masa harina, however, for the cornstarch and polenta be sure to grind down each of one so that the texture remains consistent with masa harina. Note that you should never try and use all-purpose flour. It will never be an acceptable substitute because it is made from wheat, and as we discussed above, masa harina is derived from corn.