Season the beef with salt and pepper, and place in a skillet over medium heat. Cook until evenly brown, and drain.
In a slow cooker, mix the beef broth, condensed beef consomme, wine, water, mustard, and thyme. Place beef into the liquid, and stir in the potatoes, carrots, and onions.
Cover, and cook 6 hours on Low or 4 hours on High. If you prefer a thick stew, mix the cornstarch and water together and stir into the slow cooker about 30 minutes before the end of the cooking time. Stir occasionally until thickened.