This season is marked by a surge of interest in the fungus of the species "Aspergillus oryzae", aka "koji", and this interest is shown by culinary specialists and scientists. The former experiment with "Japanese mold" when preparing various dishes, the latter try to figure out how it works. Koji fungi have been known for centuries, but how they work is still a big mystery.
Koji spores are very fond of a humid and warm environment, so mold actively multiplies on boiled rice or beans, fermenting them until they turn into new products - sauces. During this process, proactive enzymes break down proteins and digest starch, so if you put them on meat, it will not turn into liquid, but will lose the rigid structure of the fibers. Simply put, it will soften and acquire a new taste, and this process takes two days instead of the traditional 45-day aging for beef steak.
Today koji are sold immediately in packs, complete with other types of fungi, but with a similar effect. The meat must be sprinkled with this mixture, like flour, sparing no mold. And leave for 48 hours in a cool place, but no longer than 72 hours, otherwise the meat will become completely dry.
After the lapse of time, the layer of koji is peeled off and the meat is washed in cold water - it should be dark red. Such a prepared product does not need any spices, except for salt and pepper, but the meat is fried very quickly after koji, no more than 3 minutes on each side. This is due to the acceleration of the caramelization reaction, so you need to cook the steak very carefully.