Preheat oven to 350°; prick duck skin all over with a sharp fork, skewer, or thin-bladed knife; try not to hit the meat (the fat layer is usually about ¼ inch thick).
Season the duck with salt and pepper and place it, breast side down, on a rack in a roasting pan.
Roast the duck for 15 minutes, prick the exposed skin again, then roast another 15 minutes.
Brush with a little soy sauce, and then turn it breast side up.
Prick again, brush with a little more soy sauce, then roast until the meat is done, about another 45 minutes; all juices, including those from the center vent, should run clear and the leg bone should wiggle a little in its socket.
When the bird is done, an instant-read thermometer inserted into the thigh will measure about 180°.
Increase heat to 400° for the last 10 minutes of cooking if the duck is not as brown as you like.