In a 4-quart Dutch oven cook onion, red and green sweet peppers, celery, and garlic in hot oil over medium heat until tender, stirring frequently. Stir in water, sausage, undrained tomatoes, okra, gumbo mix, rosemary, thyme, and cayenne pepper, if using. Bring to boiling; reduce heat.
Cover and simmer for 20 minutes or until rice is tender. Makes 8 servings.