Rinse the corned beef brisket under cold water
Pat it dry with paper towels
Place it in a large pot or slow cooker
Add enough water to cover the brisket
Add the spice packet if included
Add optional seasonings if desired
Bring to a boil, then reduce to a low simmer
Cover and cook until tender
Skim off any foam during cooking if needed
Add vegetables such as cabbage, carrots, and potatoes near the end of cooking
Cook until the vegetables are tender
Remove the brisket from the pot
Let it rest for 10 to 15 minutes
Slice the brisket against the grain
Serve warm