The pasilla chile or chile negro is the dried form of the chilaca chili pepper, a long and narrow member of the species Capsicum annuum. Named for its dark, wrinkled skin, it is a mild to hot, rich-flavored chile. As dried, it is generally 6 to 8 inches long and 1 to 1+1⁄2 inches in diameter.

The pasilla peppers come in at around 1,000-2,500 on the Scoville scale, making them milder than other common peppers  like jalapeños and even cayenne pepper. Because of their unique flavor, pasilla peppers are commonly used in moles and salsas to add extra dimension to the other ingredients

While you might see poblano peppers labeled as pasilla peppers in the USA, there is a difference. Poblano is a fresh pepper, not dried, and it looks very much like a bell pepper—however, it is a deeper green and a bit longer and more slender than the pasilla.