Before starting, rinse your 16 oz glass jar, a mixing bowl, and a spatula thoroughly with boiling water. Place them upside down on a clean towel to air-dry completely and cool to room temperature.

Pour your dried koji grains directly into your cooled, sterilized mixing bowl (or directly into the jar). If the grains are clumped together, gently break them apart with clean hands before proceeding.

Add the sea salt on top of the koji, pour in the water, and stir thoroughly with your sterilized spatula until the salt dissolves and every single grain is hydrated. Transfer the mixture into your sterilized 16 oz glass jar.

Screw the lid on loosely (do not lock it down completely so natural fermentation gases can escape). Place the jar in a clean spot on your counter away from direct sunlight.

Once a day (or every two days), give it a good stir. Chef’s Tip: If you boil water for morning tea or coffee, scald and clean your mixing spoon with hot water first to keep daily sanitation effortless. Over the first 48 hours, the koji will drink up the water—it will naturally liquefy back into a porridge-like consistency over time.

Your Shio Koji is ready when the rice grains are completely soft when rubbed between your fingers, and the mixture smells sweet and slightly fruity (reminiscent of bananas or chestnuts). In the summer, it takes about 1 week; in the winter, it takes 10 days to 2 weeks.