Wash the knuckles of lamb, dab dry and place in a bowl. Pour buttermilk over them, cover and marinate in a cool place for 24 hours. Drain the knuckles. Clean and wash soup greens, carrots and leek. Cut leek and parsley root into slices. Cut the carrots in half lengthwise and diagonally into pieces.
Dice celery. Peel and roughly dice the onion. Heat the oil in a frying pan and fry the knuckles all around, turning them. Add diced onion, parsley root, half of the carrots and celery and fry briefly. Stir in tomato paste and season with salt, pepper and thyme. Pour in broth, bring to the boil, cover and stew for 1 3/4 hours. Peel and wash the potatoes, cut in half lengthwise and cut into thick pieces. Add the remaining vegetables to the knuckles 45 minutes before the end of the cooking time and braise with them. Peel and chop the garlic. Wash parsley, dab dry and also chop. Wash the lemon thoroughly, dab dry and grate the peel in fine strips. Mix garlic, parsley and lemon peel.
Peel and wash the potatoes, cut in half lengthwise and cut into thick pieces. Add the remaining vegetables to the knuckles 45 minutes before the end of the cooking time and braise with them. Peel and chop the garlic. Wash parsley, dab dry and also chop. Wash the lemon thoroughly, dab dry and grate the peel in fine strips. Mix garlic, parsley and lemon peel. Season to taste with salt and pepper and arrange on a deep dish. Serve sprinkled with the garlic-lemon-parsley mixture