What do you do with leftover Tonkotsu to mix it up? Ibuki style niboshi shoyu.
Take your Tonkotsu base, and gently simmer them with niboshi, mashing to extract flavor (and intentional bitterness). For this one serving, I used around 450ml of broth, and 50g large niboshi, 20g small niboshi. The large niboshi, heads and all, go in first for 30 minutes. Uncover, mash with a wooden spoon while boiling, then add in the small niboshi and steep again for 20 min. Uncover, and for 10 min, mash thoroughly while cooking. Then strain, pressing the niboshi pulp agains a fine mesh strainer.
This thing is super tasty but REALLY BITTER. I would exclude the heads and guts next time, maybe adjust the boiling temp, but I recall those niboshi innards give the broth a green hue? That was something I wanted, and failed, to get. Any ideas on getting Ibuki green color?
Brix must have been 14 when I was done. Nice bubbling on the surface, and the emulsion was strong with all that niboshi pulp. This is just further evidence that some form of ground/powdered animal protein help fat emulsify artificially into the broth. Another day another noodle.