Rice Miso Recipe

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Koji, rice or barley impregnated with "Aspergillus oryzae" culture, is fermented with mashed soybeans to make miso.
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Miso is a centuries-old ingredient that originated in China, eventually making its way to Japan.
Seven 12-ounce jars, around 5 pounds. SERVINGS


  • 3 cups soybeans
  • 1-1/2 cups rice koji
  • 2-1/2 tablespoons salt, plus
  • 1 teaspoon extra to sprinkle on surface
  • 2 cups water (save this from the cooked beans)


    • Soak the soybeans for 12 to 18 hours, then rinse, cover with fresh water, bring to the boil, then reduce to a low heat and simmer gently until soft — around 3 to 4 hours.
    • Drain, reserving the cooking liquid, then mash the beans. Keep some chunkier pieces for a rougher texture, or mash to a pulp for a smoother miso.
    • Leave to cool to room temperature. If the koji is added while the beans are hot, the beneficial mold will be killed. The mold is the culture which aids the fermentation process and transforms the mashed beans into miso, and it’s the by-products of the mold fermentation that give miso its health benefits.
    • Stir the koji and salt together, and mix both into the mashed soybeans.
    • Add some of the reserved cooking liquid, a little at a time, to loosen the mixture. Aim for the consistency of mashed potatoes.
    • Spoon mash into a clean, wide-mouthed glass or ceramic vessel. Press out all of the air as you fill the jar to eliminate oxygen, which can cause unwanted bacteria or molds to grow. If you’re careful, this shouldn’t be a problem. The salt in the miso and the proliferation of lactic acid bacteria and molds will inhibit any other growth.
    • Sprinkle the surface of the miso with a final teaspoonful of salt, then put a piece of plastic wrap directly onto the surface to keep out air. Place a weight, such as a glass pickle weight or a flat stone, on top of the plastic wrap. Put a final cover of a muslin cloth or a lid over the jar. If using a lid, remember that microbial action means gas will be given off, so it needs to be loosely fitting or have a vent in the top.
    • Place the jar somewhere dark with an even temperature, such as a closet away from heating.
    • Check every 4 weeks for unwanted mold on the miso’s surface. If there’s white mold growth, it’s harmless; scrape it away and clean the sides of the jar. Then top miso with fresh salt, new plastic wrap, and a clean weight.
    • Fermentation of this miso will take up to 12 weeks. Start tasting it around week 6 to see how it’s progressing. Once it has reached a taste that you like, remove the weight, put a tight-fitting lid on it, and store it in the refrigerator, which will virtually stop the fermentation process.

    Learn more about this unassuming superfood in The Health Benefits and Uses of Miso.

    Enjoy creating your own miso and using both light and dark versions in tasty, healthful dishes.

    Claire Jones is a freelance writer specializing in natural health and sustainability. She is a vegetarian, grows her own fruits and vegetables, and likes experimenting with fermentation.

    A great recipe for beginners, rice miso has a shorter fermentation time than other misos and a light, sweet flavor.

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