Place all of the chiles and the cumin into a medium nonstick saute pan or cast iron skillet over medium-high heat. Cook, moving the pan around constantly, until you begin to smell the cumin toasting, approximately 4 to 5 minutes. Set aside and cool completely.
Once cool, place the chiles and cumin into the carafe of a blender along with the garlic powder, oregano, and paprika. Process until a fine powder is formed. Allow the powder to settle for at least a minute before removing the lid of the carafe. Store in an airtight container for up to 6 months.
Recipe courtesy of Alton Brown, 2004