White Shiro Miso

Rinse the dried soybeans thoroughly. Place in a large bowl and cover with cold water by at least 10 cm — the beans will roughly double in size overnight. Soak for a minimum of 12 hours, ideally 18. Drain and discard the soaking water.

Transfer soaked beans to a large pot and cover with fresh water by 5 cm. Bring to a boil, skim the foam, then reduce to a steady simmer. Cook for 3–4 hours until the soybeans are completely soft — they should crush between thumb and ring finger with almost no effort. Taste one: it should be creamy, not starchy. Reserve 100 g of the cooking water before draining.

While still warm, blend or pound the cooked soybeans to a smooth paste using a food processor, blender, or traditional suribachi (grinding bowl). Add the reserved cooking water a little at a time to achieve a smooth, thick consistency — similar to very stiff hummus. No visible bean pieces should remain.

Combine the rice koji and the fine salt in a large bowl. Rub the salt into the koji with both hands for 2–3 minutes, squeezing and pressing to ensure every grain of koji is coated in salt. The salt both seasons the miso and protects against harmful bacteria during fermentation.

Combine the cooled soybean paste and the koji-salt mixture in a large bowl. Mix thoroughly with your hands, squeezing and pressing until completely uniform — no streaks of pale soybean paste visible, no unmixed pockets of koji. Form the mixture into balls roughly the size of a tennis ball by pressing firmly.

Sterilize a crock or large jar with boiling water. Throw each ball of miso mixture into the crock with force, pressing firmly to eliminate all air pockets. Smooth the surface flat. Sprinkle a thin layer of salt over the entire surface to protect it. Press plastic wrap directly against the surface, then place a weight on top. Cover the crock with a cloth and store at room temperature (18–22°C) for 3–4 weeks, tasting weekly. Refrigerate once the flavor is mild, sweet, and satisfyingly salty-umami.