This dried koji was bought at a Japanese supermarket overseas. It's labeled as "KOJI" in English and is made in California.
Sterilize the container you'll use with hot water just in case. Place the dried rice malt into the container to make the salted rice malt.
This is the 450 ml of soy sauce used the first day.
Pour the soy sauce and mix together.
Cover the container with plastic wrap, and then cover with a lid. I forgot to take a picture of it covered with a lid.
Add 50 ml of soy sauce on the second day, and mix to incorporate air into the mixture.
Mix daily so that it airs out; It will take about 10 days to 2 weeks to thicken. It is done once you can smash the rice grains between your fingers.
In order to easily preserve this, you can transfer it to a clean jar. Do not forget to sterilize the jar with boiling water just in case. It will keep for about 3 months in the refrigerator.
Story Behind this Recipe
I have made shio-koji twice before, but this time I wanted to try making the rice malt with soy sauce as in the title of this recipe. I tried it out and it was a success.
In general, the amount of soy sauce used should be the same as the rice koji. I added in most of the soy sauce on the first day, and added in the remaining portion the next day. I think the number of days it takes to ferment depends on the climate, so I just gave a ballpark figure...