Prepare rice according to package directions, omitting salt and fat. Set aside and keep warm.
Cook onion, bell pepper, and garlic in hot olive oil in a Dutch oven 5 minutes or until tender. Add Cajun seasoning, salt, and pepper. Cook 3 minutes, stirring constantly. Stir in tomatoes, beans, and water.
Cover, reduce heat, and simmer 10 minutes. Uncover and cook an additional 5 minutes. Spoon over rice.