Next time you're in a grocery store, check out the list of ingredients on the corn tortilla package. There will be corn masa, of course, but also preservatives such as calcium propionate, methyl paraben, propionic acid and potassium sorbate. Which is why they have such a long shelf life and why they sometimes taste like cardboard.
It wasn't always this way. There was a time when you got them at the local tortilleria which would cook dent corn, slake it with "cal" (calcium oxide made from superheating limestone) to soften the corn shell for easy removal, and then grind the resulting mash into a dough for making tortillas.
Nowadays, even in Mexico, it can be hard to find tortillerias that don't use reconstituted Maseca corn flour. But here in Houston, Claudia, who is originally from Mexico City, is selling corn tortillas made the old fashioned way. I met her and her daughter on a recent visit to the El Bolillo Panaderia (2428 Airline). A pound of freshly made tortillas are a fantastic bargain at $1.25. What could be better than hot tortillas with melted butter and a little salt to taste? – Jay Francis