Rinse the corned beef brisket under cold water
Place the brisket in a large pot or Dutch oven
Add enough water to cover the meat
Add the spice packet if included
Add optional aromatics such as garlic, onion, bay leaves, and peppercorns
Bring the water to a boil
Reduce to a low simmer
Cover and cook until tender, about 2.5 to 3.5 hours
Skim off any foam or fat from the surface as needed
Add vegetables like cabbage, carrots, and potatoes during the last 30 to 45 minutes of cooking
Remove the meat from the pot and let it rest for 10 to 15 minutes
Slice the corned beef against the grain
Serve with the cooked vegetables and cooking liquid if desired