Combine carrots, onion, bell peppers, garlic, and 2 tsp Cajun or Creole seasoning in slow cooker; mix well.
Trim excess fat from ribs. Cut into individual riblets. Sprinkle 1 tbsp Cajun or Creole seasoning over ribs; place in slow cooker over vegetables. Pour tomatoes with juice over ribs (slow cooker will be full.) Cover; cook on LOW 6 to 8 hours or until ribs are fork tender.
Remove ribs and vegetables from cooking liquid to serving platter. Let liquid stand 5 minutes to allow fat to rise. Skim off fat. Blend water, cornstarch, and remaining 1 tsp Cajun or Creole seasoning until smooth; stir into slow cooker. Cook, uncovered, on HIGH 15 to 30 minutes or until sauce is thickened. Return ribs and vegetables to sauce; carefully stir to coat. Serve with rice.