Preheat oven to 425 degrees.
A 5½-lb. ready-to-cook duckling
½ tsp salt
⅛ tsp pepper
A pinch of thyme or sage
A small sliced onion
Season the inside of the duck with salt, pepper, herbs, and the sliced onion. Secure the legs, wings, and neck skin to the body. Prick the skin around the thighs, back, and lower breast. Dry the duck thoroughly.
A shallow roasting pan just large enough to hold the duck easily
1 medium sliced carrot
1 medium sliced onion
Place the duck breast up in the roasting pan, strew the vegetables around it, and set it in the middle level of the oven for 15 minutes to brown lightly.
A bulb baster
Reduce oven to 350 degrees, and turn the duck on its side. Regulate heat so duck is always making cooking noises but fat is not burning. Remove accumulated fat occasionally (a bulb baster will suck it up easily). Basting is not necessary.
About 30 minutes later, or about halfway through, turn the duck on its other side.
½ tsp salt
Fifteen minutes before the end of the estimated roasting time, salt the duck and turn it breast up.
The duck is done to a medium rare if the juices from the fattest part of the thigh or drumstick run faintly rosy when the meat is pricked, and when the duck is lifted and drained, the last drops of juice from the vent are a pale rose. The duck is well done when the juices run pale yellow.
When done, discard trussing strings, and place the duck on a serving platter. Set in turned-off oven and leave the door open while preparing the sauce, which will take 3 to 4 minutes.
1½ to 2 cups brown duck stock, beef stock, or canned beef bouillon
Optional: 3 or 4 Tb port
Tilt the roasting pan and spoon out all but 1 tablespoon of fat. Add the stock or bouillon and boil rapidly, scraping up coagulated roasting juices, and crushing the vegetables, until liquid is reduced at least by half. Correct seasoning. Add optional wine and simmer a minute to evaporate its alcohol.
1 to 2 Tb softened butter
Off heat and just before serving, swirl the butter into the sauce and strain it into a sauceboat. Pour a bit of sauce over the duck, and serve.
(*) AHEAD-OF-TIME NOTE
Roast duck may wait in the turned-off hot oven, its door ajar, for about 30 minutes before serving.