The most important recommendation I give to those who are serious about taking their Mexican cuisine to the next level is to A: make your own damn tortillas and B: do it on clay instead of cast iron. Comales de barro need to be treated in order to prevent tortillas from sticking to the surface of the clay. The powdered cal helps seal the pores of the clay allowing for a nonstick surface.
unformed corn dough, tamalli
What is cal?
Cal or calcium dioxide is primarily used in Mexico for nixtamal, the pre-Hispanic technique to process whole maiz kernels for grinding into masa for tortillas. In the US this cal is also known as “pickling lime.” Not only does the cal make the maiz easier to grind, it increases the nutritional value and the toxins within the kernels themselves are reduced. We are not sure how the ancient peoples of Mexico discovered the chemical reaction, but it supported the rise of the great Mesoamerican Empires.
Mix one part cal to one part water to make a thin paste. Yes, it’s that simple. Then paint it on your comal and allow it to dry, and then repeat a second time.
When bits of the cal flake off into your tortillas or tomatillos during cooking, don’t panic, think of it as added niacin mineral intake! When the cal starts to flake off or it becomes soiled, I use a metal brush to scrape off the cal and then clean the surface with water and repaint it again.