Preheat oven to 250 degrees.
Place brisket in large roasting pan. Cover generously with Dijon mustard.
Sprinkle pickling spice over mustard. Generously cover with brown cane sugar.
Pour whiskey around brisket, being careful not to wash off sugar and mustard.
In the same manner, add enough water to fill just up to the edge of brisket.
Cover with heavy foil wrap or lid, if one is included with the pan.
Place in oven for 3 hours on middle rack.
After 3 hours, add potatoes and carrots around brisket. Re-cover and roast for another 3-5 hours.
To serve, ladle ample amount of broth into a medium sauce pan and thicken with corn starch to a glaze consistency.
Wedge heads of cabbage and steam until tender.
With a slotted serving spoon, portion potatoes, carrots and steamed cabbage.
Slice brisket against the grain after removing from pan.
Serve over cabbage wedges.