Rub ribs with mixture and set aside for at least one hour.
Put ribs on a rack in a roasting pan containing 1 1/2 cups water and roast slowly at 350 degrees for 50 minutes or until done. Do not let ribs touch the water. Add more hot water if necessary during cooking to keep the pan covered. Brush ribs with remaining sauce mixture, turn over and repeat. When the ribs are cooked, remove the water from the pan, and turn oven up to 450 degrees and brown both sides (about 15 minutes).
Cut into strips between the bones and serve with duck sauce and Chinese mustard.