A pasilla is a dried version of the chilaca chile pepper that is native to Mexico. It is narrow with a length of approximately six inches (about 15 cm) and a wrinkled appearance. The spiciness level of these chiles is typically considered to be mild to moderate.
A chilaca chile pepper is a part of the Capsicum annuum species. It is a deep shade of green when it first develops but as it gets older, it transforms into a brown color. Once a chilaca chile pepper becomes brown, it is picked and dried out. Chile peppers can be dried out using a dehydrator, an electric device that slowly heats the peppers to remove their moisture. They can also be dehydrated by being hung upside down in a dark area for about two weeks.
After the chilaca chile peppers are in their dried states, they are then referred to as pasilla, which means “little raisin” in Spanish. These dried chiles are often sliced or chopped, then used to add flavor to Mexican stews, soups, vegetable entrees and meat dishes. They impart a complex taste to dishes because they are smoky and moderately spicy with a bit of a slightly sweet flavor. One of the most traditional applications of pasilla chiles is in mole, a versatile Mexican sauce made with chiles, garlic, ground seeds or nuts, onions, and chocolate.
Whole dried chiles can also be ground up and combined with other spices to make pasilla chile powder. The chile powder is typically mixed with cumin, dried oregano, and granulated garlic. The whole chiles are usually not grown or readily exported to other regions outside of Mexico, but the powdered version is often more easily accessible to people who are not near Mexico. It is generally used to add flavor to chili, stew, or other Mexican dishes like quesadillas, fajitas, or tacos.
Other varieties of chile peppers are sometimes inaccurately labeled and sold as pasilla chiles, such as the poblano and ancho chile peppers. Poblano peppers are dark green and similar in color to young chilaca chile peppers, but they are significantly wider with a spicier taste. Ancho peppers are dried versions of poblano peppers. They may appear similar to dried chilaca chile peppers and even be mislabeled as such.