Prepare the marinade. In a bowl, mix one spoon of mustard, dried and crushed oregano, ground nutmeg, dried rosemary. Add a pinch of ground black pepper and mix thoroughly.
Prepare the duck for marinating. Without peeling it off completely, separate the skin from the muscles with your fingers. Rub the inside, under the skin and outside of the carcass with salt. Generously spread the prepared marinade under the skin and inside. Transfer the duck to a wide saucepan or pike perch, cover with a lid and marinate for 2-4 hours in the refrigerator.
Stuff the bird. Fill the carcass alternately with chopped potatoes and handfuls of cabbage. Join the edges of the skin at the back and secure with toothpicks or sew with kitchen string. Tie the wings with thread so that they naturally press against the body. Tie the legs in the same way.
Start roasting. Place the duck in a roasting bag. Make 2-3 punctures in the top of the bag with a needle and place the bird on a baking sheet. Bake in the oven for 2-2.5 hours at 200 degrees for the first hour, then reduce the temperature to 180-170 degrees. 30 minutes before it is ready, carefully, so as not to burn yourself with steam, cut the roasting bag and continue cooking until a golden crust forms.
Prepare the sauce. Pour half a glass of water into a small saucepan and bring to a boil. Pour 0.5 glass of semi-dry red wine into the heating water, let the mixture boil until it is reduced by half. Pour in 100 ml of cream and cook until the consistency of liquid sour cream. Salt and add a pinch of ground black pepper. When it boils, remove from heat and pour into a gravy boat.