Pepper and salt the veal knuckle. Sear all over in a pan with olive oil. Take out and put in the roaster. Cut the vegetables into small pieces. In the pan, fry the onions first, then the celery and carrots, and finally the leek. Put the knuckle in the roasting pan and pour on the stock and the white wine. Place in the oven at approx. 100 degrees for four hours. Pour the liquid over and over again. Take the knuckle out of the roaster after four hours and fry it until crispy for 10 minutes at 200 degrees using the grill function. Take out and let rest for 10 minutes.
For the sauce, pass the vegetables through the Lotte liquor or through a sieve. Possibly. Thicken with a little sauce bandage for dark sauces.