1. Remove the corned beef from the packaging and rinse thoroughly to remove excess salt.

2. Place the corned beef in a large pot and cover with water. Bring to a boil.

3. Reduce the heat and simmer the corned beef over low heat until tender (about 2-3 hours).

4. Meanwhile, prepare the vegetables: peel and quarter the potatoes, peel and slice the carrots, slice the cabbage into strips.

5. Add the vegetables to the corned beef and simmer for another 30 minutes until the vegetables are soft.

6. Remove the corned beef from the pot and slice. Transfer the vegetables to a serving platter.

7. Serve with mustard or horseradish.