Clean, wash and chop the carrots and celery. Drain the tomatoes, collect the juice. Dice the tomatoes. Peel and chop onions. Season veal knuckles and tie them into shape with kitchen string.
Heat the oil in a frying pan, fry the knuckles in it vigorously and remove them. Sauté half of the onion cubes in the frying fat. Add vegetables, tomato juice and tomato paste, 1/2 litre stock and 100 millilitres wine.
Put meat on top. Cover and braise in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 1 1/2 hours. Briefly blanch the bones and remove the marrow. Fry the rest of the onion cubes in the fat until transparent.
Add marrow, rice and saffron. Pour in the remaining stock and wine. Leave to swell for 20 to 30 minutes on a low heat. Add the parmesan cheese to the rice. Peel garlic. Chop parsley and garlic.
Peel the lemon, cut the peel into strips. Mix garlic, parsley and peel. Season to taste the sauce. Serve with the meat and risotto. Sprinkle with the garlic mixture.