Heat oil in a large skillet over high heat. Add turkey and brown for 2-3 minutes. Transfer the meat to your slow cooker, leaving oil in the skillet. Add the onion and bell pepper to the skillet and sauté for 1-2 minutes. Add garlic and cook one minute longer. Transfer veggies to the slow cooker. Add remaining ingredients to the slow cooker and stir. Cover and cook on low for 4-5 hours.