Put the pork knuckles in a saucepan, add enough water to cover them, and simmer with the peppercorns, bay leaves, caraway seeds and salt for about 1 hour.
In a sautéing pan, fry the diced root vegetables and onion in sunflower oil until they begin to brown.
Remove the pork from its cooking water, dab dry, add to the fried vegetables, and continue frying for a while.
Deglaze with white wine, before transferring to the oven and roasting for about 40 minutes at 200°C/ 392 °F
Remove the knuckles from the roasting tray, and use a small knife to cut off the jelly-like skin, which should then be chopped finely.
Remove the meat from the bone, and cut into small pieces.
Put half of the cooked vegetable mixture into a bowl, and mash with a fork until smooth. Mix together the meat, pork skin and mashed vegetables, and season to taste with salt and pepper.
To make a sauce, brown the rest of the cooked vegetables and knuckle bones in a hot pan before pouring in 2 liters (8 ½ cups) of water and simmering for 20 minutes.
Pass the resulting stock through a fine sieve, and then reduce it until only about ¼ is left.
Adjust the seasoning with salt and pepper before binding with the cold butter.
Using a pasta machine, roll out the noodle dough as thinly as possible.
Brush half of the rolled-out dough with a little water, place small blobs of the pork filling over this half of the sheet, and then cover with the other half of the sheet of dough.
Press down firmly, and cut out individual ravioli that should be cooked in boiling salted water for about 2 minutes and then tossed briefly in butter in a frying pan.