-
1
Blanch the pork bones in boiling water for 5 minutes. Drain, rinse under cold running water, and discard the blanching liquid. This removes blood and impurities. The bones are ready when the rinse water runs clear.
-
2
Place the cleaned bones in a large pot with 2.5 litres of cold water. Bring to a vigorous boil, then reduce to a steady simmer. Maintain the simmer throughout extraction. The broth should be clear to slightly cloudy — a full rolling boil will produce excessive cloudiness. The broth is ready when it carries evident pork richness and body; taste confirms depth without rawness.
-
3
Combine the dark soy sauce and regular soy sauce to form the tare. This is where the dish lives or dies: the tare must deliver dark colour and fermented depth without bitterness. Add the tare to the finished pork broth gradually, tasting after each addition. The correct proportion produces a dark amber broth that is authoritative and direct — not thin, not bitter. Excess tare darkens the broth through bitterness rather than depth; stop before that line is crossed.
-
4
Press the mackerel fillets with rice vinegar — the quick vinegar press constitutes the hayazushi technique. Allow the acid to work until the flesh surface loses its raw translucency. Season the sushi rice in the standard proportion. Form the rice and vinegar-pressed mackerel into pressed sushi portions. The finished pieces should carry bright acidity and clean fish flavour.
-
5
Cook the thin straight alkaline noodles in a separate pot of boiling water. These noodles cook to a point slightly softer than Hakata-style firm. Touch the noodle between two fingers — it should yield completely with no hard centre remaining.
-
6
Drain the noodles and portion into four bowls. Ladle the hot tonkotsu-shoyu broth over the noodles. Place the hayazushi portions alongside each bowl — not inside the broth. The sushi serves as palate cleanser between mouthfuls of broth; the two are eaten in alternation, not combined.