Wash the turkey leg, dab dry and season with salt, pepper and marjoram. Put the leg of turkey together with 1/8 litre water into a roasting pan and roast without lid in a preheated oven (electric cooker: 175 °C/ gas: level 2) for approx. 1 1/2 hours.
In the meantime, peel and chop the onion. Clean, wash and cut the soup vegetables into small pieces. Heat oil in a pan and fry everything over medium heat for about 5 minutes.
Add the sauerkraut and braise for another 15 minutes. Stir several times. Wash and quarter the apple and remove the core. Cut quarters into slices and add to the sauerkraut with the apple juice 5 minutes before the end of the cooking time.
Add the prepared apple and sauerkraut to the turkey leg 15 minutes before the end of the cooking time. Garnish with parsley as desired.