Rinse the corned beef brisket under cold water
Place the brisket in the crockpot with the fat side up
Add the seasoning packet that came with the corned beef
Add enough water, beef broth, or a mix of both to cover the brisket halfway
Add optional vegetables such as onions, carrots, and potatoes around the meat
Cover the crockpot with the lid
Cook on low for 8 to 10 hours or on high for 4 to 6 hours
Check that the meat is fork-tender before removing it
Transfer the corned beef to a cutting board 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