Trim fat from meat. Place in a 4- to 6-quart pot; add juices and spices from package. Add enough water to cover meat. Add Guinness, black pepper and bay leaves (if your corned beef comes with its own package of spices, add it and omit pepper and bay leaves). Bring to boil. Reduce heat. Simmer, covered, about 2 hours or until almost tender.
Add potatoes, carrots and onion to meat. Return to boil. Reduce heat. Simmer, covered, for 10 minutes.
Add cabbage. Cover and cook 15 to 20 minutes more or until tender.
Slice meat against the grain, and serve with mustard.Makes 4 Source: