Preheat the oven to 350 degrees F (175 degrees C).
Place the corned beef brisket into a Dutch oven, and season with pickling spice. Fill with enough water to cover the roast, and place the lid on.
Bake for 2 1/2 hours in the preheated oven. Then, remove it from the Dutch oven and place on a broiler pan. Preheat the oven's broiler.
While the meat is roasting, mix together the corn syrup and mustard in a small saucepan. Bring to a boil, and cook over medium heat until slightly thickened, about 5 minutes.
Spread the mustard glaze over the roast, and broil for 5 to 7 minutes, until the glaze is shiny.
