Hiroshima oyster nabe (kaki nabe)

Step 1: Put 4 ¼ cups water and ⅓ oz kombu (dried kelp) in a wide, shallow pot (a donabe or a casserole about 26 cm across) and leave to soak while you prepare everything else.

Step 2: Mix 3 ½ oz white (shiro) miso, 1 ¾ oz red (aka) miso, 2 tbsp sugar and 2 tbsp mirin in a bowl to a thick, smooth paste. Mirin contains a little alcohol; for an alcohol-free paste use 2 tbsp water and an extra 1 tsp sugar instead.

Step 3: Put 14 oz shucked oysters in a bowl with 2 tbsp potato starch or cornflour and 1 tsp salt and stir gently with your fingers for 30 seconds until the starch turns grey. Rinse in two changes of cold water and drain on kitchen paper. If you bought oysters in the shell, discard any that are open and do not close when tapped.

Step 4: Bring the kombu water slowly to a bare simmer over medium heat. Lift out the kombu just before it boils, add ½ oz bonito flakes (katsuobushi), turn off the heat and leave for 3 minutes, then strain through a sieve lined with kitchen paper. Pour the broth back into the pot.

Step 5: Spread the miso paste in a thick band, about 3 cm deep, around the inside wall of the pot just above the broth line, so it sits like a bank around the edge.

Step 6: Arrange 14 oz Chinese leaf (napa cabbage), 1 leek or Japanese long onion, 10 ½ oz firm tofu, 6 fresh shiitake mushrooms and 3 ½ oz enoki mushrooms in sections in the pot. Cover and simmer over medium heat until the cabbage stems are tender.

Step 7: Add 3 ½ oz crown daisy (shungiku) or spinach and push them down into the broth. Scrape a little miso from the rim into the broth with a ladle, taste, and keep adding until it is as rich as you like.

Step 8: Lay the oysters in the broth and simmer gently for at least 3 minutes, until they are plump, the edges have curled and the flesh is firm and opaque right through. Common mistake: boiling the oysters hard or for a long time; they shrink and turn rubbery, so keep the pot at a gentle bubble and serve them as soon as they are cooked.

Step 9: Bring the pot to the table and ladle oysters, vegetables and broth into small bowls. When the pot is nearly empty, add 14 oz cooked udon noodles to the last of the miso broth and heat for 2 to 3 minutes for a final course.