Miso (Akamiso)

Last Updated on

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.

The most practical 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. (It is difficult, but not impossible, to make your own koji.) Local Asian markets usually carry dried koji. You can also find online merchants like this one.

If using fresh 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 below is a long red miso (akamiso) style and in this version, I made it with adzuki beans rather than soybeans.

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

Basic Recipe

Red Miso (non-soybean)
Prep time: 
Fermentation time: 
Yield: 2 quarts/2 liters
  • 2 cups/~500 ml (by volume) or 14 oz/400g (by weight) dried beans (chickpeas, adzuki, anasazi or other legume)
  • 20 ounces /567g (by weight) dried firm granular koji
  • ½ cup/125ml plus 1-2 Tbsp. (by volume) or 5 oz/140g (by weight) plus 1 ounce/30ml fine sea salt
  • filtered water
  • 1 Tablespoon/15 ml mature miso
  • half-gallon or larger glass or ceramic vessel
  • jar or wine bottle which fits inside mouth of vessel
  • paper grocery bag, or tight-woven canvas or cloth bag (in which vessel can fit)
  • Stapler
  • masking or packing tape
  1. Soak beans in 2.5 cups/600 ml of filtered water overnight (up to 24 hours).
  2. Drain beans from soaking liquid.
  3. Bring 8 cups/2L of filtered water to a boil, then add beans and reduce heat to simmer.
  4. Cook for 45 to 60 minutes, until done. (Nothing against soybeans, but they take much longer to cook than other beans-- several hours in a pressure cooker or 5 hours on stove.)
  5. Drain beans, RESERVING 1½ cups of the cooking liquid.
  6. Add beans to a large mixing bowl.
  7. Mash the beans, leaving it somewhat chunky (not as smooth as refried beans).
  8. Dissolve ½ cup of salt in 1½ cups/375 ml of the cooking liquid you reserved. Let brine mixture cool to 100°F/38°C.
  9. Add mature miso to the brine. Stir until it is incorporated.
  10. In a separate bowl, add brine and then stir in koji.
  11. Add koji-brine mixture into beans. Mix well.
  12. Spritz or otherwise wet the inside of the vessel, then add remaining sea salt (1-2 Tbsp.) to the bottom and sides of the vessel.
  13. Pack the vessel with the mixture, ensuring there are no air bubbles in the mixture (they can breed bad mold!) Tap vessel on a towel or wooden cutting board several times to ensure that any air bubbles in the mixture come to the surface.
  14. Add remaining salt to the top layer of the mixture.
  15. Add a weight such as a glass bottle or plate to the top of the mixture. This will weigh it down and allow the tamari to rise to the surface.
  16. Carefully place the vessel into a paper bag. Staple and then tape it shut so no bugs can enter. Write the date on the bag.
  17. Store it in an unheated space (like the garage) for at least six months (until the next cool season), and over one summer. You can ferment as long as 24 months.
One Year Later
  1. Carefully open the bag and remove the vessel. Drain the tamari (if any liquid is formed on the top) into another bowl and then into a bottle. Cherish this!
  2. Remove the weight. Scoop out any funky mold from the top surface.
  3. Pack into another glass jar. Use a layer of parchment paper in between the metal lid and the lip of the jar (miso corrodes metal).
  4. For longest life, store in the refrigerator. Alternately, you can store in the cupboard.


The making of miso…

Our Youtube playlist of miso videos!