Wash the knuckles, dab dry and make a grid-like incision in the shavings. Rub with salt and pepper. Place on a grid over the fat pan and roast in a preheated oven (electric: 175 °C/ gas: level 2) for approx. 3 hours.
In the meantime, peel, wash and dice the potatoes for the vegetables. Cook in boiling salted water for about 12 minutes. Dice bacon. Peel onions and cut into rings. Clean and quarter the savoy cabbage. Cut out the stalk.
Cut leaves into strips, wash and drain. Skip the bacon, fry the onions in it until golden brown and take them out. Fry cabbage in bacon fat, deglaze with cream and 1/8 litre water. Continue cooking for about 10 minutes.
Season with salt, pepper and mustard. Fold in the potatoes. Serve the knuckles and vegetables sprinkled with bacon and onions and freshly chopped parsley.