Preparation: Mix the salt, 5-Spice, MSG and sugar together and rub inside of bird with the mixture. Fold up the tail into the bird and using an upholstery needle or turkey skewers and string, close up the duck sealing all openings.
Blanch the duck in 3 qts of boiling water pouring the water over the duck about 8 times. Hang up to dry for 3-4 hours.
Combine red wine vinegar (or rice wine), water, honey, soy sauce and lemon in a pot and bring mixture to a boil. Turn heat to low and let simmer for 20 minutes. Using a ladle, pour this mixture over the duck several times until it is completely coated. Hang duck in front of a fan for 4-5 hours or overnight sans fan.
Place duck on a greased rack and roast for 20 minutes in at 400 F. Turn oven down to 375 F and continue to roast - 25 minutes per lb. total time. This includes the first 20 minutes. (A 4 1/2 lb duck would take approx. 1 1/2 hrs.)