Omit oil and omit browning chicken and cooking onion, celery, and garlic. In a 3 1/2- or 4-qt. slow cooker combine the chicken, onions, tomatoes, broth, celery, tomato paste, Cajun seasoning, and garlic. Cover and cook on low 5 to 6 hours or on high 2 1/2 to 3 hours. If using low, turn to high. Stir in rice and bell pepper. Cover and cook 30 minutes more or until pepper is tender. Stir in cooked shrimp and parsley. Season to taste. If desired, top with celery leaves and hot sauce.