Do we use chili powder (a mixture of ground chiles, cumin, oregano, salt, garlic powder, and other spices), or chile powder: ground Ancho chiles?

Hi Drew! For this dish, chili powder (the blend, salt-free, if you can find it!) allows for a bit more depth of flavor in the sauce, due to the different spices in the mixture. That said, really, either will work. If you happen to use chile powder (as in, ground/powdered chiles), I'd taste it to see how to spicy it is, and probably start with less in the dish—something like 2 teaspoons—and add more to your liking as the dish braises. Hope this helps!