Heat oil in a large skillet over medium-high heat. Add bell peppers, onion, mushrooms and ¼ teaspoon salt; cook, stirring often, until beginning to brown, about 8 minutes. Add flour, tomato paste, garlic, oregano and crushed red pepper; cook, stirring constantly, until fragrant, about 1 minute. Stir in wine; cook, stirring and scraping up any browned bits, for 30 seconds.
Transfer the mixture to a 6-quart slow cooker. Stir in chicken, tomatoes, broth and capers. Cover and cook on Low for 8 hours.
Transfer the chicken to a clean cutting board; let cool for 5 minutes. Remove bones and return the meat to the slow cooker. Stir in olives and the remaining ¼ teaspoon salt. Cover to keep warm.
Meanwhile, bring water to a boil in a medium saucepan over medium-high heat. Whisk in polenta; cook, stirring often, until thickened, about 3 minutes. Remove from heat and stir in Parmesan. Serve the chicken and sauce over the polenta, topped with basil.
Serving size: 1½ cups chicken with sauce and ½ cup polenta
448 calories;14 g fat(4 g sat); 5 g fiber; 39 g carbohydrates; 38 g protein; 49 mcg folate; 175 mg cholesterol; 7 g sugars; 0 g added sugars; 1,802 IU vitamin A; 70 mg vitamin C; 89 mg calcium; 3 mg iron; 666 mg sodium; 708 mg potassium
Vitamin C (117% daily value), Vitamin A (36% dv)
Carbohydrate Servings: 2½
Exchanges: 4½ lean protein, 2½ vegetable, 1½ starch, ½ fat