Place a 2kg piece of boned ham, neatly tied, in a very large pan with 2 leeks, a carrot, 2 ribs of celery, 2 litres of apple juice, a cinnamon stick, 9 black peppercorns, 6 or so parsley stalks and a couple of bay leaves. Bring to the boil, turn down to a simmer then scoop off the froth that floats on top. Cover partially with a lid and leave it to get on with things for a couple of hours, checking from time to time that it isn't bubbling too fiercely. After 60 minutes' cooking, check the ham for tenderness. For the sauce make a roux with 25g each of butter and flour, add 500ml of milk (the cooking water is too salty) and stir until smooth. Simmer, stirring regularly for 10-15 minutes, then add in two handfuls of chopped parsley. Serve the ham in thickish slices with the parsley sauce.
To remove any risk of saltiness, cover the ham with water, bring to the boil then pour the water away, rinse and return to the pot, then cook as above. Add a squeeze of lemon to finish the sauce. Leaving the ham in the cooking liquor to cool will ensure that the meat stays juicy.
Flavour the ham's cooking liquor with crushed juniper berries or a cinnamon stick. Use chopped dill instead of parsley in the sauce. Serve the ham in thick slices in a bowl with some of the cooking broth stirred through with chopped herbs. Keep plenty for serving cold, in very thin slices with homemade chutney.