Heat flour and oil in a Dutch oven over medium-low heat; cook for 5 minutes or until lightly browned, stirring frequently with a whisk. Add onion, bell pepper, celery, thyme, sausage, and garlic; increase heat to medium-high, and cook for 5 minutes, stirring mixture frequently. Add ground red pepper and chicken; cook for 1 minute. Stir in marinara sauce and chicken broth; bring to a boil, stirring frequently. Cover, reduce heat, and simmer 20 minutes or until chicken is tender. Remove from heat; stir in green onions. Serve over rice.