01 - Place the corned beef brisket in a large pot or Dutch oven. Add the spice packet, bay leaves, peppercorns, mustard seeds, garlic, and onions.
02 - Pour in water to cover the beef by about 1 inch. Bring to a boil, then reduce heat to low. Cover and simmer gently for 2.5 hours, skimming foam as needed.
03 - Add potatoes and carrots to the pot. Simmer for 20 minutes until beginning to soften.
04 - Add cabbage wedges. Continue cooking for 20-25 minutes, until all vegetables are tender and the corned beef is fork-tender.
05 - Remove the corned beef and let rest for 10 minutes before slicing against the grain into thin slices.
06 - Arrange sliced beef and vegetables on a large platter. Serve with a ladle of broth if desired, alongside grainy mustard or horseradish sauce.