Red Miso (Akamiso)

Miso is a bean paste made by mixing beans (soybeans traditionally), salt, and koji, a grain (usually rice) which has been inoculated and fermented with a mold, Aspergillus Oryzae. The flavor and complexity of miso is unmatched even compared to other fermented dishes. It is at once umami (savory), sweet, salty, and powerful.

Aspergillus oryzae under microscope

There are many varieties of miso, from sweeter “white” misos (which are less salty and ferment for a few weeks), to this “red” miso (akamiso) which is salty, and  measured in YEARS of fermentation. The reddish brown colors occur due to bacterial action and enzymatic processes that occur during miso’s long fermentation. A summertime is considered a year, so if you make a miso in February and finish in December, it is a “one-year” miso.

During the process, brine called tamari (from the Japanese tamaru, literally “collect” or “puddle”) is usually expressed. It can be drained off and used separately as a flavoring agent. Traditionally, miso makers would never sell the tamari from their miso, instead keeping this highly coveted treat for themselves. (Once you’ve had tamari harvested from your own miso, you will know why!)

It can be used in miso soup, as a marinade, in salad dressings, etc.

Koji, enzymatic powerhouse

The most simple way to make your own miso is to first buy koji, a grain (rice or barley) which has already been inoculated with the mold culture. Local Asian markets usually carry dried (also clled firm dried granular) koji. You can also find koji from online merchants like this one. or this one.

Rice inoculated with koji (from Asian market, $9)
pre-made koji, available online

If using fresh or homemade koji (good on ya!), use 28 ounces koji rather than 20, and 1 cup ounces soaking liquid (instead of 1 1/2c), as there is more moisture from fresh koji and less is required to rehydrate the grains.

This recipe is for a long red miso (akamiso) style and in this version, I made it with adzuki beans rather than soybeans.

You want to shoot for about 710 grams of beans cooked. In my tests, different beans end up with varying levels of hydration. So if you’re using one of these beans, you can start with the following DRIED bean weights:

  • Soybean: 368 grams (193% increase during cooking)
  • Azuki: 430 grams (165% increase)
  • Chickpea: 332 grams (214% increase)
  • Peanut: 483 grams (147% increase)

Basic Recipe

Red Miso

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Prep Time 12 hours
Fermentation Time 360 days
Makes 1.5 liters (quarts)


  • 450 grams (2 cups) dried beans like chickpea, adzuki, or other legume)
  • 315 grams (2 cups) dried firm granular koji OR
  • 360 grams fresh koji
  • 160 grams fine sea salt
  • 15 ml (1 Tablespoon) mature miso
  • filtered water


  • half-gallon or larger glass or ceramic vessel
  • weight(s) which fits inside mouth of vessel
  • paper grocery bag or tight-woven canvas or cloth bag (in which vessel can fit)
  • Stapler or masking or packing tape


  • Soak beans in 3 times the weight of filtered water overnight (up to 24 hours).
  • Drain beans from soaking liquid.
  • Bring 1/2 gallon (2 liters) of filtered water to a boil, then add beans and reduce heat to simmer. Cook until soft (cooking time varies by bean).
  • Drain beans over a colander placed over a heat-proof container to capture the cooking liquid. Add beans to a large mixing bowl.
  • If using dried koji, dissolve 160 g salt in 400 ml of the cooking liquid you reserved. If using fresh koji, dissolve 80 g salt into 200 ml cooking liquid. Let brine mixture cool down to 100°F/38°C.
  • Mash the beans, leaving about 1/4 of them intact.
  • Add mature miso to the beans. Stir until it is incorporated.
  • Once bean mixture has cooled down down to 100°F/38°C, add the warm brine and then stir in koji. Mix well for a few minutes. The koji will absorb much of the cooking liquid.
  • You should be able to form balls with the mixture that stick together. If they crumble in your hand, add more of the cooking liquid.
  • Sprinkle water on the inside walls of the fermenting jar/vessel, then quickly add sea salt to the bottom and sides so it sticks to the inside of the jar.
  • Pack the vessel with the mixture, ensuring there are no air bubbles in the jar.
  • Once packed, tap vessel on a towel or wooden cutting board several times to ensure that any air bubbles in the mixture come to the surface.
  • Add remaining salt to the top layer of the mixture.
  • Add a weight to the top of the mixture. This will weigh it down and allow the tamari to rise to the surface during fermentation.
  • If using, wrap the top of the vessel in a cloth or canvas swatch, and tightly secure it with a rubber band, bungee cord, or tape). Or place the vessel into a paper or canvas/cloth bag. Staple and/or tape it shut so no insects can enter.
  • Write the starting date on the bag or affix a label to the side of your vessel. Set a calendar appointment for the next cool season to check your miso!
  • Store it in an unheated space for at least six months (until next cool season), and over one summer. You can ferment as long as 24 months.

Post-Fermentation (6 months to 1 Year Later)

  • Carefully open the bag and remove the vessel.
  • Remove the weight. Scoop off any funky mold from the top surface.
  • Blend into a smooth paste using a food processor or powerful blender. Add a small amount of filtered water if mixture is too thick to blend.
  • Pack contents into a glass jar. If using a metal lid, store with a layer of parchment paper between the metal lid and the lip of the jar.
  • Store in the refrigerator. Lasts several years there.
Have you made this recipe?Mention @fermentersclub or tag #fermentersclub!


The making of miso…

Ready to learn more? Take one of our classes!

To learn all about this wonderful Japanese culinary tradition, pick up The Book of Miso by William Shurtleff.



5 thoughts on “Red Miso (Akamiso)

  1. Pingback: Miso Soup (Vegan) – Fermenters Club

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  3. Marguerite Reply

    I fear I have gotten in way over my head. I am not familiar with any of the terms you are using. Miso – right, Japanese restarurant …soup! That’s about it. I thought I might learn to make sauerkraut. Can I learn to do that here? I’ve heard you need to be near the ocean to make decent sour dough bread. Is that true?
    Set adrift. Marguerite

    • Austin Post authorReply

      Hi Marguerite,
      Welcome to fermenting!

      Sure, check out our sauerkraut recipe here. It’s easier than you think!

      You can make sourdough anywhere! It may taste different when it’s near the ocean as opposed to say, the mountains, but the yeast is in the air everywhere.

      Miso is a fermented paste that is used to make soup (i.e. in Japanese restaurants), but can also flavor other dishes too.

      • Marguerite Reply

        Thanks, I guess the best thing to do is to just slowly wade on in. I am working on some sourdough starter now. I made sourdough bread years ago from a starter that was being passed around but have long since lost it. I am definitely interested in making my own. I had heard it was the ocean air that makes San Francisco sourdough so tasty. I like miso soup but had no idea what it consisted of or how it was made. I didn’t realize it was a seasoning. Saurkraut is one of my favorites. I would love to try it. Is it just the fermentation that makes it sour? I always assumed it had vinegar in it. I’m not sure how I found you but, I am very intrigued with the whole fermenting thing. I have a small vegetable garden so I am always experimenting with different ideas.

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