Chop all the vegetables roughly (you can use almost any root vegetables and greens).
Put everything in an ovenproof dish, along with peppercorns, bay leaves, water, and white wine.
Rub salt into the pork shank and place the shank in the dish on top of the vegetables.
Place the dish in the lower part of the oven at 120-150 degrees Celsius (248-302 degrees Fahrenheit) in a conventional oven for 4 hours.
Baste the shank regularly with the water/stock from the dish.
After 4 hours, turn the oven up to 200 degrees Celsius (392 degrees Fahrenheit) (fan) for 30 minutes.
When the shank is done, take it out of the oven. Pour the liquid from the dish into a pot and remember to remove the bay leaves.
Put all the vegetables into a blender and blend until smooth.
Use the vegetable puree for the sauce along with the liquid from the dish. Optionally, season with a bit of cream, lemon juice, gastrique, vinegar, sugar, salt and pepper.