Soybeans fermented with Bacillus subtilis until they're sticky, stringy and pungent — nutty, cheesy, faintly of ammonia. Eaten over rice for breakfast across much of Japan.
pungent · nutty · stringy · faintly ammoniac
Kinds
Small-bean (kotsubu)
The usual kind, for rice.
Chopped (hikiwari)
Broken beans — milder and quicker to mix into things.
Japanese and Korean grocers, frozen in small tubs with mustard and sauce. Thaw in the fridge.
Worth knowing
Stir it hard before seasoning — dozens of times — until it's thick with white strings; the flavour mellows as it does. Add it at the end of cooking, if at all.