Rinse the corned beef brisket under cold water to remove excess salt.
Place it in a large pot or slow cooker and cover with water.
Season and Cook:
Add the seasoning packet, or use mustard seeds, peppercorns, and bay leaves.
For stovetop: Bring to a boil, then reduce to a simmer. Cover and cook for 3–4 hours, or until the beef is tender.
For slow cooker: Cook on Low for 8 hours.
Add the Vegetables:
About 30–45 minutes before the corned beef is done, add the cabbage, carrots, and potatoes to the pot or slow cooker.
Continue cooking until vegetables are tender.
Serve:
Remove the beef and slice against the grain for maximum tenderness.
Serve with the cooked vegetables and spoon some of the flavorful broth over the top.
