How to Make Miso Paste from Scratch

When we were in Japan in October of 2019 we were lucky enough to do a WorkAway with a lovely family in Iwanai. Akiko-san (Aki) the mom, taught us about Japanese cuisine like gobo root, kinako, and miso. She spoiled us with delicious home cooking and when we asked about her miso soup and if she used a store bought paste, she showed us her own homemade miso paste which has been maturing for 3 years! And that inspired us to make our own.

Miso Making Basics

Things to Know Before Making Your Own Miso

Thank you to Aki for allowing us to share her recipe, but first let’s go over some basics of making miso paste. Sadly, you won’t be able to make this today and use it for dinner. Depending on which miso paste you are making you’ll need at least several months before using it and the longer you wait the better the flavor will be.

Temperature is Crucial

So if you’re still with us and we didn’t lose you, hurray! Miso paste is made by the fermentation of soybeans and koji, a mold grown on grains, which is used to make sake, soy sauce and miso. Some important factors are going to be temperature; the before combining the mashed soybeans and koji, you’ll need to make sure the mash isn’t too hot or it will kill the koji. Another temperature point to keep in mind is when storing the paste, it would be best in a cold dry area.

Don’t Grow Any Friends

Another important factor is starting with a sterile container so you don’t end up growing other things with your miso. Similarly, make sure to pack your miso tightly so there are no air pockets or you may have some internal mold growth that can make the paste come out musty. You will also need to weigh down your miso paste so it does not expand and explode…. since as it ferments it releases things!

Use Delicious Water

The final thing to keep in mind, is that the water you use is very important. One of the reasons why Aki’s miso is so good, she explained, is because of her water source: the natural spring water coming from Mt Yotei. The quality of water is very crucial to making miso paste from scratch, so don’t just use any old tap water unless you live by a spring. Essentially, use the best tasting water you have access to. With all that in mind, let’s get started on this recipe!

Aki’s Homemade Miso Recipe

  • 1kg soybean
  • 1kg koji
  • 300g sea salt, set aside 2TBS of the salt for topping the miso
  • 400ml soybean water (water from cooking the soybeans)

How to Make Homemade Miso Guide

  1. Wash and then soak soybeans for at least 18 hours. Make sure to soak them using tasty water!
  2. After soaking, sterilize your miso container and set up your fermenting space (pick a dark, dry and cool spot).
  3. Pour your soybeans and water into your cooking pot with enough water to cover the beans.
  4. Cook the soybeans until soft enough to smush between your fingers. On the stovetop it will take about 3 hours. In a pressure cooker it will take about 30 minutes after it reaches pressure.
  5. When the soybeans are cooked through, drain the soybeans, setting aside at least 400ml of the soybean water. We recommend saving the rest of the water for some tasty soup; bean water makes a great stock starter.
  6. Mash the soybeans with a potato masher or in a food processor. Then allow the mash to cool to room temp, or below 100F.
  7. Mix your koji and sea salt together.
  8. When the soybean mash has cooled, add in the koji and salt mixture, slowly adding the soybean water.
  9. Once well combined, pack the mix into tight balls and chuck them into your container. Pack the mix down very tightly so there are no air pockets anywhere.
  10. When all your miso is packed in, sprinkle remaining 2TBS salt across the top. Seal the miso with plastic wrap so that none of it is exposed to the air.
  11. Weigh down the miso then cover and place into your fermentation spot.
  12. Allow to ferment for 3 months, then give the miso a mix and pack it back down and ferment for another 6 months.
  13. After 6 months you can give it the first taste and use! Don’t forget to mix it and pack it down again. Continue to mix and pack down your miso every 3 months. The longer you allow it to ferment, the stronger the flavor will get, see how long you can keep maturing your miso!
homemade miso: mix koji and salt with soybean mash
Mix koji and salt with the room temperature soybean mash

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