Remove neck and giblets from the duck. Rinse thoroughly and pull and remaining quills. Trim excess fat up to either opening (you can slice this up and render it for duck fat if you're saving the fat). Slice a diamond pattern into the duck's back. Prick the skin all over with a knife. Truss the legs together. Sprinkle with salt.
Roast in a 300F oven, breast side up. After one hour, prick the skin all over and flip breast side down. After the 2nd hour, prick the skin all over and flip breast side up. After the 3rd hour, prick the skin all over and flip breast side down.
During the 4th hour, combine remaining ingredients and stir over high heat until thick and syrupy. After the 4th hour, pull the duck out. Raise oven temperature to 400F. If you're saving the fat, now's the time to rescue it from the pan. Blast at 400F for 10 minutes, then pull out and cover with the honey-soy glaze. Blast another 5-7 minutes until it turns mahogany brown. Let it rest 15 minutes, carve, and eat!