Place chopped onion, garlic, red bell pepper, jalapeno pepper, ground cumin and chipotle pepper into the bottom of a crockpot.
Cover this mixture with brown rice and boneless, skinless chicken breasts.
Pour diced tomatoes, with juices, and chicken broth over the chicken breasts.
Turn the crockpot to Low and cook until the chicken is cooked through, about 8 hours.
Remove the chicken breasts from the crockpot and, using two forks, shred the chicken. Return the chicken to the crockpot, along with the black beans and frozen corn.
Cook on Low for an additional 30 to 60 minutes. Stir in chopped cilantro and fresh lime juice. Season with salt and pepper.
Serve with chopped avocado, tortilla chips and sour cream, if desired.