In a saucepan, combine the soy sauce, mirin, and sake.
Add the kombu and slowly bring the mixture to a gentle simmer.
As soon as you see small bubbles forming, turn off the heat.
Add the bonito flakes and let steep for 5 minutes.
Strain through a fine mesh strainer and return the liquid to the pan.
Add ginger, white pepper, smashed garlic, and shiro miso.
Simmer gently until fragrant — do not boil aggressively.
Strain again and finish with rice vinegar.
Taste it. Adjust if needed. If you prefer more salt, add a splash of soy. This is a base recipe — make it your own.
Let the tare cool and store in the refrigerator. It improves after a day or two.