1. Preheat oven to 350°.
2. Combine cumin, oregano, 1/2 teaspoon ground red pepper, and 1/4 teaspoon salt; rub evenly over pork. Heat a large ovenproof skillet over medium-high heat. Add 2 teaspoons oil to pan, and swirl to coat. Add pork, and cook 5 minutes, browning on all sides. Place pan in oven, and bake at 350° for 20 minutes or until pork is done. Remove pork from pan; let rest 15 minutes. Cut pork into 1/2-inch pieces.
3. Combine 1 cup onion, 1 cup broth, tomatillos, 1 garlic clove, and serrano in a medium saucepan. Bring to a boil; reduce heat, and simmer 15 minutes or until tomatillos are tender. Cool for 10 minutes. Combine tomatillo mixture, cilantro, lime juice, and 1/4 teaspoon salt in a blender; process until smooth. Pour into a large measuring cup.
4. Place skillet over medium heat. Add 1 teaspoon canola oil to pan; swirl to coat. Add the remaining 2/3 cup onion; cook for 3 minutes or until tender, stirring frequently. Add remaining garlic clove; cook for 30 seconds, stirring constantly. Add remaining 1/3 cup broth, and cook for 1 minute, scraping pan to loosen browned bits. Add black beans; cook 2 minutes, stirring frequently. Cool slightly. Place black bean mixture in blender. Pulse 15 times, scraping occasionally until mixture is a thick puree.
5. Heat a medium nonstick skillet over medium-high heat. Add the remaining 1 tablespoon oil to pan; swirl to coat. Combine remaining 1/8 teaspoon red pepper, brown sugar, and plantain in a medium bowl, tossing to coat plantain. Add plantain mixture to pan; sauté for 3 minutes or until golden brown, stirring frequently. Cool slightly; finely chop. Combine pork and plantain mixture in a medium bowl.
6. Spread 1/3 cup tomatillo mixture in the bottom of a 13 x 9inch glass or ceramic baking dish coated with cooking spray. Heat tortillas according to package directions. Spread about 1 1/2 tablespoons black bean puree down center of each tortilla; top with about 2 tablespoons pork mixture. Sprinkle each tortilla with 1 tablespoon cheese; roll up. Place seam-side down in baking dish. Pour remaining tomatillo mixture over filled tortillas; sprinkle with remaining cheese. Bake at 350° for 25 minutes or until cheese melts and filling is thoroughly heated.