Wash the whole duck and dry it well outside and inside with a paper towel. Then put the duck on some paper towels to soak up any water excess. (If you have bought a frozen poultry leave it at room temperature to defrost).
Mix 1 pinch of salt, 1 pinch of ground garlic, 1 pinch of ground coriander seed (these species taste perfect on the poultry) and 1 tsp of pepper with 7 tbsp of mustard.
Rub generously the bird with the spices mixture inside and outside.
Put the duck in a glass bowl and top it with a piece of cling film. Leave it in the fridge for at least 24-48 hours to marinate.
Before roasting the duck, remove it from the fridge 30 minutes ahead.
Stuff the duck with one big quartered onion and 6 halved garlic cloves.
Place the duck in a baking sleeve with the breast-side facing downwards. Close hermetic the sleeve and arrange it on a roasting pan.
Preheat the oven at 360 °F (180°C). Roast the bird for 2 hours.
Once it is done, remove the roasted duck from the oven, open careful baking sleeve and withdraw the bird from it and place it on a serving plate. Leave it uncovered to rest for about 10 minutes before slicing.
Garnish this mouth-watering poultry with Sauerkraut, mashed potato or any other side dish you like.
Enjoy your meal!