Roast for 15 minutes. Reduce heat to 177°C. Turn the duck. Roast for 30 minutes. Turn the duck again. Roast for 20 minutes. Add a pinch of salt and turn again. Roast for 15 minutes.
Boil vinegar and sugar over high heat for 5 minutes. Remove from heat. Add half a cup of duck stock. Simmer for one minute, stir. Add the remaining stock, the Port and the orange peels. Simmer for 4 minutes. Pour the orangeliqueur.