Begin by cooking the knuckle. Place in a deep pan and cover completely with cold water. Bring to a simmer over a medium-high heat, skimming any residue that appears on the surface of the liquid

Add the whole celery stick, onion, carrot and 1 of the bay leaves. Bring everything back up to a simmer and cook for 2 hours and 30 minutes, topping up the water if needed during cooking

After this time, remove the knuckle and set aside to cool. Strain the cooking liquid through a sieve and weigh out 1.75l to use later as stock for the soup (any leftover stock can be frozen for future use)

Place a large heavy-bottomed pan over a medium heat and melt the butter. Add the celery and onion mixture and allow to sweat down, without colour, for 4–5 minutes

Add the green split peas and continue to cook for another 3–4 minutes, then add the strained ham stock, remaining bay leaf, chopped garlic and a pinch of ground white pepper and salt

Bring up to the boil, then simmer for 2 hours and 30 minutes until the peas are fully cooked through. Leave the soup chunky for a rustic texture or blitz with a hand blender to create a smooth soup

Shred or chop the meat from the cooked knuckle into fine strips. Serve the hot soup garnished with the ham with some crusty bread on the side