Technically speaking, masa harina means "dough flour" in Spanish, though you'll often see it referred to as corn flour as ...

These homemade tortillas start with a dough made from whole-grain corn masa that is shaped and then ... She shared the above recipe for nixtamalizing your own corn.

but masa harina is the unexpected star here. It's rather well known as a special kind of finely ground corn flour used to make the dough for recipes like tortillas, pupusas, or tamales ...

Corn masa flour is available from good supermarkets, as is chipotle sauce (I recommend the La Morena brand. You can use their whole tinned chipotle peppers instead, just use much less).