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

Prep Time 12 hours
Fermentation Time 360 days
Course condiment
Cuisine Japanese
Makes 3 liters (quarts)


  • food processor or high speed blender


  • 3 1/2 cups (600 g) dried beans like chickpea, adzuki, or other legume
  • 2 1/2 cups (567 g) dried firm granular koji OR
  • 3 cups (650 g) fresh koji
  • 1 1/4 cups (300 g) fine sea salt
  • 3 tbsp (45 ml) mature miso


Prepare Mixture

  • Soak the beans in 10 cups (2.5 liters) of filtered water overnight (or up to 24 hours)
  • Drain beans from soaking liquid.
  • Bring 1/2gallon (2 liters) of filtered water to a boil, then add beans and reduce heat to simmer. Cook until soft, about 30 to 60 minutes (exact cooking time varies by bean).
  • Save the bean cooking liquid. Place a colander over another pot, mixing bowl or other heat-proof container, then use it to drain the beans and capture their cooking liquid. Place the drained beans in a large mixing bowl or put them back in the cooking pot once it has cooled down.
  • Let the cooking liquid mixture cool down to 100°F / 38°C.
  • Mash the beans, leaving about 1/4 of them intact.
  • Reserve 1 tbsp (15 g) of salt for later, and stir the rest of the salt into the bean mixture.
  • Add the mature miso to the beans. Stir until it’s well incorporated.
  • Stir the koji into the bean mixture.
  • Once the cooking liquid has cooled down, add 3 cups (750 ml) of liquid to the mixture if using dried koji, or 1 3/4 cups (420 ml) liquid if using fresh koji.
  • Mix well for 5 to 10 minutes in order to allow the koji to absorb the cooking liquid.
  • Once the miso is well mixed, you should be able to form it into balls that hold together without any liquid coming out when you gently squeeze them. If the miso crumbles in your hand, add more cooking liquid to the mixture, stir well, and then try the squeeze test again.
  • Spritz, sprinkle, or spray filtered water on the bottom and inside walls of the fermenting jar/vessel, then sprinkle some of the reserved salt on the bottom and sides so that an even layer of salt sticks to the bottom and insides of the jar.

Prepare for Fermentation

  • Pack the vessel with the miso mixture, ensuring that there are no air bubbles as you go. Leave 1 inch (2.5 cm) of room between the mixture and the top of the vessel.
  • Tap the vessel it on a folded towel or wooden cutting board several times to remove any air pockets. Make sure the top surface is even and flat.
  • Add a layer of salt to the top.
  • Add a weight (fermentation weights, a plate, etc.) to the top of the mixture. This will press the miso down and allow the tamari to rise to the surface during fermentation.
  • Set the vessel on a plate or in a shallow food storage container.
  • Affix a label to the side of your vessel with the current (start) date.
  • Cover the container with a tea towel or dishcloth to keep out dust and flies. Secure the cloth with twist ties or a rubber band. If you’re using a small-batch fermentation kit, apply the fermentation lid per the instructions. Alternately, place the vessel and plate into a paper grocery bag or canvas/cloth bag. Staple and/or tape it shut so that no insects can enter. If using bag, write the start date on the outside of the bag or attach another label to the bag.
  • Set a calendar appointment for the start of the next cool season to harvest your miso!
  • Store the miso in an unheated space for at least 6 months (until the next cool season) and at least over one summer.

Post-Fermentation (6 months to 1 Year Later)

  • If stored in a bag, carefully open the bag and remove the vessel.
  • Remove the lid and weights from the vessel. Scoop off any scum from the top surface of the miso.
  • 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!
  • Blend the miso into a smooth paste using a food processor or high-speed blender. Add a small amount of filtered water if mixture is too thick to blend.
  • Pack the miso into glass jars. If you’re using a metal lid, place a layer of parchment or wax paper between the metal lid and the lip of the jar before you secure the jar.
  • Store the miso in the refrigerator, where it will last for several years.
Keyword koji, miso, umami


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

  2. Pingback: Miso Soup | Fermenters Club

  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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