Make the seasoning: In a medium bowl, mix the chili powder, onion powder, cumin, paprika, garlic powder, oregano, red pepper flakes, salt and pepper.
1 Tablespoon chili powder, 2 teaspoons onion powder, 1 ½ teaspoons ground cumin, 1 ½ teaspoons sweet paprika, 1 teaspoon garlic powder, 1 teaspoon dried oregano (mexican preferably), 1 ½ teaspoon dried red pepper flakes, 1 teaspoon kosher or sea salt, ½ teaspoon freshly ground black pepper