1. Get a large oven or stockpot. Combine the brisket, spice package contents, brown sugar, and bay leaves; cover with water, then place it in.
2. Proceed to bring the content to a boil. Then reduce the heat to low and let it simmer for 2 hours, covered.
3. You can now return to a boil with the potatoes and carrots. Reduce the heat to a low again and cook, covered, for 30-40 minutes until beef and veggies are cooked.
4. Return the saucepan to a boil with the cabbage. You can remove potatoes and carrots before adding cabbage if the pot is full. (You can reheat before serving)
5. Reduce heat to low; cover and cook for 15 minutes until cabbage is soft. Remove the veggies and corned beef and set them aside, keeping them warm.
6. Strain and set aside 1½ cups of the cooking liquids for horseradish sauce. Skim fat from saved juices, remove and discard any residual juices.
7. Melt the butter in a small saucepan – over medium heat. Go on to whisk in flour until it appears smooth.
8. Get 1 cup of the reserved juices, then whisk it in gradually.
9. Bring to a boil – frequently stirring – with the sugar, vinegar, and horseradish. Then cook it until the sauce has thickened – make sure you keep stirring through it.
10. You can add little extra cooking juice if you want. Then season to taste with more sugar, vinegar, or horseradish sauce.
11. Get a sharp knife and cut the steak into slices across the grain.
12. You can serve this dish with a side of vegetables and a dipping sauce.

You can watch this video recipe to know how to cook cabbage for corned beef.