Classic Shio Koji (Fermented Rice Seasoning Paste)

1.Place the dried rice koji in a sterilized 1-quart glass jar and add the sea salt. Use clean hands to massage the salt into the koji grains for 2 minutes until they feel slightly damp and fragrant.

2.Pour the filtered water into the jar and stir with a clean wooden spoon until the salt is fully dissolved. Ensure all koji grains are submerged; if they float, press them down with the back of the spoon.

3.Cover the jar loosely with its lid (do not tighten) or a clean cloth secured with a rubber band to allow for gas exchange. Place the jar in a cool, dark spot on your counter, ideally between 68°F and 75°F (20°C-24°C).

4.Stir the mixture thoroughly once a day for 7 to 10 days using a clean spoon to redistribute the enzymes and prevent mold. If the koji absorbs all the liquid in the first 48 hours, add 1-2 tablespoons of filtered water to keep it moist.

5.Check for doneness after 7 days: the rice grains should be soft enough to crush easily between your thumb and forefinger, and the liquid should be thick, milky, and smell sweet like bananas or pineapple.

6.For a smooth paste, pour the fermented mixture into a high-speed blender and process on medium for 30 seconds until creamy. Transfer to an airtight jar and refrigerate immediately; it will keep for up to 6 months while the cold temperature slows further fermentation.