To cook the ham, place the hocks in a large pot and cover with cold water. Bring the water to the boil then drain. This removes excess salt and any impurities from the ham and will yield a cleaner stock. Add fresh cold water to the pot and bring back to the boil. Cover and simmer for three to four hours, or alternatively place the pot in the oven and cook gently at 130 degrees/gas ½ for three to four hours.

When the hocks are cooked the meat should fall off the bone. Allow them to cool down in the stock. When cool, carefully remove the ham from the stock and take the meat off the bones. Set the meat aside. Strain the stock through a sieve.

For the celeriac: Peel it and leave whole. Put the salt in a bowl and add the egg whites, mixing to combine into a paste. Place the celeriac on a roasting tray and cover with the salt/egg white paste. Bake in the oven at 190 degrees/gas 5 for 45 minutes. Remove and set aside, allowing to cool. Remove the salt crust from the celeriac and cut it into chunks. Set the chunks aside for later.

For the barley: Strain the barley from the water used for soaking. Place the barley into a pot and cover it with water. Add the other ingredients. Bring to the boil and simmer for three to four minutes, or until cooked. Strain through a sieve and set aside, removing the garlic and thyme.

For the mushroom broth: Place a large pot on the stove and heat it up. Cut the onions in half (around the equator of the onion, not through the root). Add a tablespoon of oil to the pot, then add the onions, flesh side down. You want to char the onions in the pan for 10-15 minutes to develop a rich barbecue flavour. Slice the shitake and portobello mushrooms and add to the pan. Add the garlic, and another tablespoon of oil if necessary. Keep the heat on moderate to high and roast the mushrooms in the pan for 10-15 minutes.Add the thyme then cover with the reserved ham stock. Add the procini.

Bring to the boil the simmer gently for 35-40 minutes. Add the kombu and remove from the heat.

Cover the top of the pot with cling film and set aside for 15 minutes. This will improve the flavour of the broth and allow the kombu to infuse. Strain the broth, discarding the solid ingredients. Set the broth aside.

To finish: Warm the broth on the stove then add the barley, celeriac and the meat from the ham hocks. Add the wholegrain mustard to taste. Finely chop the lovage and parsley, then add to the broth. Check the seasoning. It will need a touch of cracked black pepper. There should be enough salt in the broth due to the ham hocks. Serve with crusty bread with extra virgin olive oil or truffled creme fraiche.