Most of my Mexican food knowledge comes from the year or so I spent in Baltimore for work. I've mentioned this before, but my coworker G's wife who is an amazing cook, would spoil G with home cooked lunches and sometimes G would spoil me. The white corn tortillas that I shared years ago was a result of conversations with G who explained that his wife would make masa (with dried corn and lye) but in a pinch, she would use masa harina.
In browsing through my grocery store's website, I realized that I'd been buying masarepa to make my tortillas instead of masa harina. I'd just been grabbing the bag of white cornmeal from the latin section without even thinking about it. This led me down some insane Google hole; I was trying to figure out the difference between masarepa, masa harina, harina de maiz, and basically anything with the word "harina" (which means flour in Spanish) and "maiz" (which means corn) and "masa" (which means dough).
In the end, I didn't make any intelligent conclusions because, as it turns out, combinations of these words are used in several different countries and can mean several different things. And, I figured it really didn't matter, as long as the end result was edible. I bought a bag of Goya-brand yellow "harina de maiz" (which I suspect is literally just cornmeal, as it had a recipe for corn muffins on the back) and used Goya-brand white "masa harina" to make these yellow corn tortillas and they turned out awesome. I guess the moral of the story is that research is great but the execution is what actually matters; or something like that.
1½ cups yellow harina de maiz
½ cup masa harina (or masarepa)
¼ teaspoon salt
1¼ to 1½ cups hot water