Poblano chilies (Capsicum annuum) are a mild chili pepper originating in the state of Puebla, Mexico. When dried, it’s called ancho chili. The chilies have a dark green color that look great in any dish. So rather than using green bell peppers, I substituted Poblano chilies, which gave the dish a very mild spiciness. I used a bottled black bean sauce, but you can easily make your own.