Dongzhi lamb soup (yangrou tang)

Step 1: Soak 2 ¼ lb lamb bones and 1 ⅓ lb boneless lamb leg or shoulder in a large bowl of cold water for 20 minutes to draw out the blood, then drain.

Step 2: Put the bones and meat in a large pot, cover with cold water and bring to the boil over a high heat. Boil for 5 minutes, skimming off the grey foam, then drain and rinse everything and the pot well.

Step 3: Return the bones and meat to the clean pot with 12 ½ cups water, 2 ⅛ oz fresh ginger, 4 spring onions and 1 tsp white peppercorns and bring to the boil over a high heat.

Step 4: Keep at a hard, rolling boil, lid ajar, for 25 minutes, until the broth turns cloudy and milky white. Common mistake: keeping it at a gentle simmer; the fat never emulsifies and you get a clear broth instead of a creamy one. Top up with boiling water if it drops below the bones.

Step 5: Lower to a lively simmer, cover and cook for 70 minutes more, until a chopstick slides easily through the lamb.

Step 6: Lift out the lamb, let it rest for 5 minutes, then slice it thinly across the grain. Discard the ginger, spring onions and bones.

Step 7: Stir 2 tsp salt into the broth and taste. Divide the sliced lamb between bowls, ladle the boiling broth over and finish with ½ tsp ground white pepper, 1 small bunch fresh coriander and 2 tbsp chilli oil, if using.