Cut the onion into small cubes and the apples into small pieces. Remove larger pieces of fat from the duck legs and rub the outside with salt or fondor. Then let it rest for about 10 minutes. Fry in a saucepan with the greasy side down (use a little oil). Turn after approx. 3-4 minutes and sear the underside for 3 minutes. Add about a quarter of the onion cubes and pour in the broth.
Let the legs stew slowly for about 45 minutes. Turn after 45 minutes and braise again for 30 minutes.
Now add the remaining diced onions, apple pieces and marjoram and stir. Braise again for about 10 minutes on each side. Then remove the legs and keep them warm. Thicken the sauce in the pot with the cornmeal and briefly bring to the boil. Season the sauce to taste and put the legs in for about 5 minutes so that everything is warm.