Spicyness:

Mulato chile is derived from a very dark colored poblano chile variety that is almost never sold fresh, as it is better preserved when dried to preserve the mulato chile flavor.

It is a brown chili pepper that has an almost chocolate-like flavor, is somewhat spicy, and is usually used to make moles.

Although it is physically very similar to Ancho chillies, it cannot be substituted for it, as the flavors are very different. It is easy to confuse the Mulato variety with Ancho.

To distinguish them, you have to open them and look at them with the naked eye: Ancho is red inside and Mulato is brown inside. The Mulato chile is known in Oaxaca as the black Ancho chile, Oaxaca is known for Mole in general, and in Escuincla Chiapas there is a variety of Mulato chile that is very black called Chocolate chile.