For the honey mustard glazed ham, soak the gammon in a large bucket or pan of cold water overnight. This will help to reduce the salt content. The next day remove the gammon and discard the soaking water.
Place the gammon in a large pan and cover with fresh water, then bring to the boil. Once the water is boiling drain and then refill the pan with cold water.
Add the halved and peeled onions, whole peeled carrot, celery, halved garlic bulb, peppercorns and the bay leaves to the water. Bring to a slow simmer and leave simmering for 2.5 hours.
Top up with boiling water if needed. Skim any scum off the top during the cooking process.
Probe at regular intervals, it should be a minimum of 63ºC. Do not cook above 70ºC as it will dry out. Leave to cool for an hour in the liquid.
Reserve 2 pints of the liquid for the parsley sauce and pour the remainder of it away (or use for pea soup). Place the ham in a roasting tray. Remove the skin, ensuring you leave a thin layer of fat, then score in the criss-cross pattern. Stud with cloves in each square. Set the oven to 180ºC/Gas mark 4.
To make the glaze - mix the oil, honey, mustard and sherry vinegar together in a mixing bowl. With a spoon smear some of the glaze over the ham and bake in the oven for 10 minutes.
After 10 minutes baste with more of the remaining glaze and juices that have dripped off the ham. Repeat the process again every 10 minutes for the next 30 minutes.
Wash, peel and remove any black spots from the potatoes. Cut the potatoes into even sizes, ensuring there are straight edges and right angles. This is easier to achieve with large potatoes.
Place the potatoes in a large pan and cover with cold water. Season the water well. It should taste like the sea. Bring the potatoes to a slow boil. Cook until they are nearly cooked and then drain the water.
Once drained, place the potatoes back in the pan, put the lid on and then shake firmly, so that they start to break up on the outside, not all the way through.
Place a heavy based roasting tray over two hob rings, add the duck fat and melt. Put the potatoes in the tray and turn over with a fish slice. You are looking to achieve a golden crisp colour on the potatoes. The colour does not need to be even all over.
Once the potatoes have a good amount of colour and before they start to burn place them in a hot oven on 220ºC/Gas mark 8 and roast until golden all over. When ready to serve, sprinkle with chopped sage and marjoram.
For the bread sauce, peel a small onion and stud with the cloves. Place the garlic, onion and bay leaves into a medium sized pan with the milk and bring slowly to the boil to infuse.
In a medium sized pan melt the butter. Then add the peeled and chopped celeriac and coat in the butter. Strain the infused milk over the celeriac and simmer for 15-20 minutes until tender. Do not worry if the milk splits.
Season with salt and white pepper. Once the celeriac is tender, blend in the liquidiser and keep warm until ready to serve.
Go back to the ham and check that it is golden all over. Once golden rest for 10 minutes and then it's ready to carve.
For the broccoli, bring a large pan of salted water to the boil (tasting like the sea). Cook the broccoli in the salted water for 3-4 minutes until the stem is just tender.
Then place into cold water to stop the cooking immediately. After 5 minutes drain well, it should still be reasonably firm.
Toast the hazelnuts in a pan, then remove from the pan and roughly chop. Add to the hazelnut oil.
Toss the broccoli in olive oil and season with Maldon salt, place under a hot grill and turn after 1-2 minutes.
Don’t worry if some of the leaves start to burn just a little, the bitter notes are good. Once hot and slightly charred, dress with the hazelnuts and serve when ready.
For the parsley sauce, peel and slice the banana shallots and garlic, sweat down in the butter in a medium sized pan. Add the ham stock and bring to the boil.
Chop the flat parsley including the stalks. Place the ham stock and parsley in a liquidizer and blend for a 3-4 minutes. Add the xanthan gum, this will stop the sauce splitting when cooling.
Season with black pepper and serve warm with the rest of the components.