Wash the knuckles and place them in a large pot. Fill with water so that the knuckles are covered. Peel onion and lard with cloves. Wash the herbs. Put them in the pot with the onion and season with salt.
Bring to the boil and simmer at low heat for about 2 hours. Skim off any foam that develops.
Remove the knuckles from the stock and dab dry. Heat the oil in a large frying pan. Sauté the knuckles in it over medium heat while turning them. Add honey and caraway and caramelise until golden brown.
Add broth and braise covered at low heat for about 1 hour.
Peel, wash and chop the potatoes and celery. Cook in boiling salted water for 20-30 minutes. Heat milk and butter in a pot. Add potatoes and celery, mash coarsely, season with salt, pepper and nutmeg.
In the meantime clean, wash and chop the spring onions. Add them to the knuckles about 20 minutes before the end of the stewing time and cook with them.
Take the knuckles out of the oven. Season to taste with salt and pepper. Serve with puree and garnish with parsley leaves if desired.