Thoroughly rub pork shoulder with mixture of salt, seasoned salt, garlic powder, black pepper and M.S.G. Place fat-side up on rack in shallow pan. Roast at 160ºC . for 40 minutes. per pound to 90ºC . on meat thermometer. Remove skin and score fat in diamond pattern. Pour mixture of honey, ginger and horseradish over scored fat. Return to oven. Roast for 20 minutes longer until well-glazed.