This chile is like the smaller brother of the chipotle. It, too, is a smoked, dried chile made from a small jalapeno grown in the state of Michoacan. It is very hot, but not as hot as the chipotle and, also like the chipotle, is often sold canned as chipotle en adobo. It is widely used in Veracruz. Unfortunately, the name pasilla is used in parts of the United States to refer not to a dried chile but instead to the fresh poblano.
Greek oregano tastes like pizza, while Mexican oregano tastes like Mexican food.
Do not substitute one for the other. It is easily found in Mexican and Latin American markets. Mexican oregano develops its full flavor when toasted in a dry skillet until fragrant. On its own, epazote, a deep green herb with serrated leaves, has a strange medicinal smell, almost like kerosene. It is essential in a wide range of dishes, including a large number of Veracruz specialties, as well as black beans.