In a skillet, heat oil over medium heat, then add onions, garlic, cumin, oregano, pepper and salt. Cook for about 5 minutes, stirring occasionally.
Stir in tomatoes, brown sugar and broth, and bring to a boil.
Pour over the chicken, turning the chicken to coat. Cover and cook on low for 5-6 hours or on high for 2 1/2 to 3 hours. (Until the juices run clear when the chicken is pierced.)
Stir in the red pepper, corn, cilantro and 1 tsp of the chipotle pepper and lime juice. Then cook on high for about 20 minutes (until the red pepper is tender).