Core and coarsely chop tomatoes (makes about 4 cups); set aside. In a large saucepan, heat oil until hot. Add onion. Cook, stirring occasionally, until tender, about 5 minutes. Stir in chilies, garlic, cumin, oregano, sugar, cloves, red pepper and the 4 cups reserved tomatoes. Reduce heat and simmer, stirring occasionally, until the tomatoes are softened, about 5 minutes. Add chicken broth; bring to a boil, reduce heat, simmer, covered, to blend flavors, about 15 minutes. Add beans and chicken; cook until hot, about 5 minutes. Garnish with sour cream, shredded Cheddar cheese, diced tomatoes, and chopped cilantro, if desired.