Remove the sinews from the meat and use a knife to insert shallow cuts into the white edges on both sides.
In a tray, add 2 tablespoons of shio-koji, then cover with a sheet of gauze. Place the meat on the gauze. Cover the meat with another sheet of gauze and add another 2 tablespoons of shio-koji on top.
Allow to marinade for 15 to 20 minutes, then cook. It burns easily, so cook on high heat while keeping away from the flames.
A reader showed me a good way to cook this. Please try it. Check out steps 5 and 6.
Cook on high heat for 2 to 3 minutes, enough to slightly turn golden brown. Then reduce to low heat and cook for 3 minutes. Then turn off the heat and let cook with the remaining heat.
Letting the meat cook in the leftover heat keeps the meat juicy. This is what I was told, so I'm citing it here.
I used pork belly for yakiniku. It's thinner than cutlet meat so you only need to marinate for 15 minutes. It's softer and easier to eat than sirloin.
Story Behind this Recipe
My mother taught me how to cook this meat by using shio-koji.
It's best if you use a bleached cotton cloth type gauze, but if you don't have any, then a gauze handkerchief works. When cooking sirloin it tends to contract, so please add the small cuts. For the next time you make this, please adjust the marinade time accordingly.