Put the ham hock in a large pan with the bay leaves. Cover with water, bring to the boil and cook over a low-medium heat for 2 hrs, until the meat is very tender. Top up the pan with more water as needed while the ham cooks. Alternatively, cook the ham hock in a pressure cooker for 30 mins. Remove the ham and strain the stock into a jug. Remove and discard the rind, shred the meat and set aside until needed.

In the same pan, heat the oil over a medium heat, add the onion and cook for 10 mins, then add the apple and celeriac. Taste a little of the ham stock – if it is very salty, add water to dilute it. You’ll need about 1 litre in total (freeze any that’s left over for making more soup or risotto). Pour in the stock, bring to a simmer and cook for 20 mins or until the celeriac is very tender.

Add the crème fraîche and mustard to the soup, then blitz with a hand blender. Check and adjust the seasoning if necessary.

Warm the ham hock in a pan or the microwave. Serve the soup topped with a swirl of crème fraîche and a few drops of good olive oil, and a pile of ham hock – or make a ham and cheese toastie for dunking. Leftover ham hock will keep frozen for up to two months.