Preheat the oven to 180 °C (350 °F).
Sear the duck legs in the duck fat for 6 to 8 minutes (skin side down first) on medium heat in a large skillet with a lid. While searing, season to taste with salt, pepper, nutmeg and garlic powder.
Moisten with some of the duck stock and turn heat down to low. Cover and braise for 30 minutes.
Remove the legs from the pan and set aside on a plate. Add the cabbage to the pan and season with salt to taste.
Add the sherry and potato slices to the pan. Lay the duck legs on top and cover.
Cook for 45 minutes in the oven, then remove the lid and continue cooking for another 45 minutes. To brown the top of the legs, put them under the broiler at the end of cooking.
Remove from the oven and serve immediately with sesame green beans.
