Tonkotsu ramen

Method

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Blanch and scrub the bones

1. 1

   Put the trotters and bones in a pot of at least 10 l, cover with cold water and bring to a boil over high heat. Boil hard for 10 minutes, until a thick grey-brown scum covers the surface.

2. 2

   Drain in the sink and rinse each piece under cold running water. Scrub away the dark clotted blood with a brush or chopstick, especially inside the cracked femurs and around the trotter joints. Scrub the pot clean too: any scum left on the sides will grey the broth.

Boil for 10–12 hours

3. 3

   Return the bones to the clean pot with about 5 l cold water, enough to cover them by a few centimetres. Bring to a boil over high heat, skimming off the foam for the first 20–30 minutes. After that, stop skimming: the fat floating now is part of what makes the broth creamy.

4. 4

   Keep the pot at a hard, rolling boil, the whole surface churning, with the lid ajar to slow evaporation. Keep a full kettle beside it. Every hour or so, top up with boiling water to keep the bones just covered, and scrape the bottom with a sturdy wooden spatula so nothing sticks and scorches.

5. 5

   After about 3 hours the broth will be beige and cloudy, and by 5–6 hours the trotters will be soft and collapsing. From then on, each time you top up, mash the trotters and bones against the side of the pot with the spatula or a potato masher to break them down and release more marrow and collagen.

6. 6

   With 2 hours to go, add the ginger and leek greens. For the last hour, stop topping up so the broth reduces and concentrates.

Cook the chashu (about 4 hours before the end)

7. 7

   Tie the pork belly into a neat block with butcher's twine and lower it into the boiling broth. Boil for 2 hours, until a skewer slides in easily.

8. 8

   Meanwhile, bring the soy sauce, mirin, sake and sugar to a boil in a small pan, bubble for 1 minute and pour into a container just big enough to hold the pork. Lift the cooked pork into the warm marinade and leave it for at least 1 hour, turning it every 20 minutes. If you won't eat within 2 hours, refrigerate it in the marinade once cool.

Make the tare and the kikurage (while the broth boils)

9. 9

   For the tare, soak the kombu in the water and sake in a small pan for 30 minutes. Heat slowly over low heat until small bubbles appear at the edge, about 10 minutes, then lift out the kombu. Add the mirin and simmer for 1 minute. Turn off the heat, add the katsuobushi and steep for 5 minutes, then strain, pressing lightly. Stir in the salt until completely dissolved. You should have about 200 ml.

10. 10

    Soak the kikurage in plenty of warm water until soft and swollen, 20–30 minutes. Trim off any hard knobs, slice into thin strips, then blanch for 1 minute in boiling water. Drain and toss with the soy sauce and sesame oil.

Finish the broth

11. 11

    After 10–12 hours the broth should be opaque, ivory-white and thick enough to coat the back of a spoon, with the bones breaking apart. Strain it through a fine sieve into a clean pot, pressing hard on the solids and pushing the soft trotter through for extra body.

12. 12

    Measure it: you need 350 ml per bowl, and you'll probably have about 2 l. If it tastes thin or you have far more, boil it hard to reduce; if it's very thick, whisk in a little boiling water. Whisk it hard, or blitz it with a stick blender for 30 seconds, until smooth and creamy.

Assemble

13. 13

    Bring a large pot of unsalted water to a rolling boil and fill the bowls with hot water to warm them. Keep the broth at a gentle boil; unlike a clear broth, tonkotsu is happy bubbling, which keeps it emulsified. Slice the chashu thinly, about 3 mm.

14. 14

    Empty the bowls, put 35 ml (2 tbsp plus 1 tsp) tare in each, then ladle in 350 ml boiling broth and whisk briefly.

15. 15

    Cook the noodles two portions at a time. For kata (firm), boil for about 30 seconds less than the packet says, usually 40–60 seconds for fresh Hakata-style noodles; a strand should be cooked through with a slightly firm core. Drain well, shaking hard.

16. 16

    Drop the noodles into the soup and top with chashu, kikurage, spring onions and sesame seeds, crushing the seeds between your fingers as you scatter them. Serve at once, with beni shoga on the table.

17. 17

    For kaedama, cook about 60 g of extra noodles the same way when someone is nearly out of noodles but still has soup, and drop them straight into the bowl. Add 1 tsp tare if the soup now tastes thin.