Place meat, pepper, mustard seeds, bay leaf, whole cloves, and 2 Tablespoons dark brown sugar in a large stockpot. Fill with enough cold water so the meat is covered by 4 inches. Bring to a boil. Reduce heat, cover, and simmer until the meat is fork tender, about 3 hours. Remove the meat to a greased roasting pan.
Preheat oven to 450 degrees F.
Add the cabbage, onions, carrots, parsnips and potatoes to the broth. Bring to a boil, reduce heat, cover and simmer until the vegetables are tender, about 20-25 minutes.
Combine 2 Tablespoons dark brown sugar, Maine Maple Syrup and Caramelized Onion Mustard. Brush over the meat, coating all exposed surfaces generously.
Roast for 20 minutes, until browned. Slice and serve at once surrounded by boiled vegetables. Serve with additional mustard.