Rinse the corned beef under cold water
Place the corned beef in a large pot or Dutch oven
Add enough water to cover the meat
Add the spice packet if included
Bring to a boil over medium-high heat
Reduce to a low simmer
Cover and cook for 2.5 to 3.5 hours, until tender
Add vegetables like potatoes, carrots, and cabbage during the last 30 to 45 minutes of cooking
Remove the corned beef from the pot
Let it rest for 10 to 15 minutes
Slice the corned beef against the grain
Serve warm