In a large pot combine meat, spice bag and enough cold water to cover. Bring to a boil, reduce heat and simmer 2 hours.
Add all vegetables but the cabbage and simmer 30 minutes more. Or until vegetables are tender.
Remove brisket from pot and set the cabbage wedges on top of the vegetables, cover and cook until the cabbage is tender , approx. 15 minutes.
Slice the brisket while the cabbage is cooking. If the brisket cools too much in the carving time place slices back in pot on top of the cabbage to heat through.
To serve: Place vegetables on a large platter surrounding the sliced corned beef. Pass broth in a separate serving bowl or gravy boat.
Horseradish Cream
Combine sour cream and horseradish in a small bowl. Salt and pepper to taste.