Season the chicken with salt and pepper. Add 1 tablespoon oil to a Dutch oven or large soup pot set over medium heat and cook the chicken breasts on each side until cooked through in the center. Remove to a cutting board and cool.
Add 2 tablespoons oil to the pot over medium heat and cook the onion and pepper (season with salt and pepper) until tender about 5 minutes. Add the garlic and saute until fragrant.
Add the sweet potatoes, tomatoes, black beans and corn. Season with the chile powder, cumin, red pepper flakes, about 1 teaspoon coarse salt and 1/4 teaspoon black pepper.
Cut the chicken into bite-sized pieces and add to the pot. Bring to a simmer and cook about 35 minutes, stirring every so often and adding more seasoning as needed until sweet potatoes are tender.
Serve with shredded cheese, sour cream and/or tortilla chips.