Combine water and beef base in a 6-quart slow cooker and stir well.
Add prime rib, potatoes, frozen vegetables, red wine, onion, ketchup, celery, carrots, garlic, parsley, thyme, salt, and pepper. Cook on Low until vegetables are tender, 6 to 8 hours.
Notes
Cook’s Note
I use LeGout beef base from a restaurant supply store rather than beef broth or beef bouillon. I find it adds better flavor. Adjust the amount to your taste.