Set the oven to 350°F. Stir the broth and the contents of seasoning packet in a roasting pan. Place the beef, fat side-up, into the pan. Spread the mustard on the beef. Sprinkle with the brown sugar. Cover the pan.

Bake for 2 hours. Arrange the onions, carrots, potatoes and cabbage around the beef in the pan.

Bake, uncovered, for 1 hour or until the beef and vegetables are fork-tender. Let stand for 10 minutes. Place the beef and vegetables into a serving dish. Strain the broth mixture and serve with the beef and vegetables.