Homemade miso is in the making; soybeans, salt, and koji mixture in a glass jar.

Homemade Miso

Course: How to
Cuisine: Japanese
Keyword: miso
Prep Time: 30 minutes
Cook Time: 1 hour 30 minutes
Soaking Time: 18 hours
Total Time: 20 hours
Servings: 3 kg (6.6 lb)
Author: Nami

Make Homemade Miso from scratch with just 3 ingredients and a little patience. My simple step-by-step instructions on How to Make Miso will guide you through this process. Once it is made, you can use the amazing fermented paste for many delicious Japanese dishes!



  • 650 g soybeans (1.43 lb)
  • 1000 g rice koji (5 cups) (2 Cold Mountain packages)
  • 375 g sea salt (13.2 oz)
  • ½ Tbsp sea salt (for sprinkling)



  1. Gather all the ingredients. Besides this, you will need 2 large bowls (one should be a very big one), 1 strainer, Instant Pot (or pressure cooker or a large pot), a clean cloth, alcohol (shochu or vodka), a potato masher (or a food processor), a 1-gallon glass jar to put miso in, and a bag of 1 kg (2.2 lb) table salt.

    How to Make Miso Ingredients
  2. Gently wash the soybeans thoroughly several times under running water. P.S. The foam seen in the images here is not soap.

    Homemade Miso 1
  3. In a large bowl, add the rinsed soybeans and fill the bowl with filtered water to about 5 inches (10 cm) above the beans. Soak the soybeans for 18 hours.
    Homemade Miso 2
  4. Drain the beans. Look how large the beans are now. The right soybean is before soaking, and left two soybeans are after 18 hours of soaking. After soaking, total soybeans weigh 1435 g.

    Homemade Miso 3
  5. Add the soybeans into the inner pot of Instant Pot. Fill the pot with filtered water to about ½ inch (1.2 cm) above the beans (roughly 8 cup line of the pot).

    Homemade Miso 5
  6. Close the lid and set HIGH pressure for 20 minutes. Make sure the steam release handle points at “sealing” and not “venting”.

    Homemade Miso 5
  7. STOVETOP OPTION: Alternatively, you can cook the beans on the stovetop. Bring to a boil over high heat, skim off the surface scum, lower to a simmer, and cook for about 3-4 hours, uncovered, until the beans are soft. Add water as needed during simmering to keep the soybeans submerged in just enough water.

  8. Meanwhile, in a large bowl (You will add mashed soybeans in this bowl, so use your largest bowl/pot/container/dish), combine the rice koji and salt with your hands.
    Homemade Miso 6
  9. Also, put some alcohol (shochu, vodka, soju, sake, etc) on a clean cloth and wipe inside the jar you will put miso in.
    Homemade Miso 7
  10. Once the pressure cooking is finished, release the pressure naturally. It will take about 30 minutes till pressure comes down completely and you can open the lid.
    Homemade Miso 8
  11. Test if the beans are done, by pressing a bean between a pinky and thumb. If it is mashed nicely, it’s ready. Drain the soybeans over a bowl to capture the cooking liquid. NOTE: When you are mashing the beans, you may need some cooking liquid, so save about 1 cup just in case. Ideally, it’s best not to use the cooking liquid at all (for this particular recipe, which is designed to make miso without adding cooking liquid). Water in the miso has a higher risk of potentially causing mold growth in the miso.
    Homemade Miso 9
  12. While the soybeans are still hot, transfer some of the soybeans back in the Instant Pot inner pot and mash them with a potato masher (pestle or bottle, etc). Do this process in batches so it’s easier to mash nicely.
    Homemade Miso 10
  13. If you have a food processor, process some soybeans until they are paste form. Do this process in batches so it’s easier to process.
    Homemade Miso 11
  14. ONLY if the soybeans look really dry, add a small amount of cooking liquid. As I mentioned earlier, it’s best if you don’t add it in this recipe. Scoop out the paste and continue with next batch.
    Homemade Miso 12
  15. Mashed soybeans must be warm/room temperature (NEVER hot) before combining them with the koji because hot soybeans can kill koji mold. Mashing takes time unless you make a small batch, so you don’t need to worry about the soybeans being hot in this recipe.

    Homemade Miso 13
  16. Add the warm (not hot!) mashed soybeans into the bowl with the koji and salt mixture.
    Homemade Miso 14
  17. Knead well to distribute the rice koji and salt with mashed soybeans. Take time to do this process until it’s mixed well.
    Homemade Miso 15
  18. Using your hands, form tennis ball-sized balls with mashed soybeans.

    Homemade Miso 16
  19. Put each ball into the container and mash it with your fist and knuckle to ensure that all air pockets have been eliminated. Do one layer at a time, and make sure to press down tightly. If you have a glass jar, you can see if you miss any pockets by looking from the side of the jar.

    Homemade Miso 17
  20. Repeat this process until all the balls are pressed tightly in the jar. Pat down the surface with flat of your palm or knuckle to smooth out. Make sure you have a space left for the weight on top of the miso. If your jar/container is too small, use another container. Clean the inside surface walls of the container with a shochu-soaked cloth/paper towel to deter mold.
    Homemade Miso 18
  21. Sprinkle ½ Tbsp of sea salt on top of the surface.
    Homemade Miso 19
  22. Place a plastic wrap on top of the surface and make sure to cover nicely. I use my adjustable drop lid (otoshibuta) to hold down the plastic wrap while I work on covering the edges and remove it when I was done.
    Homemade Miso 20
  23. Put heavy objects (or rocks) on top of the miso. I put 1 kg (2.2 lb) of table salt (cheaper than the sea salt) in a plastic bag and put it on top.

    Homemade Miso 21

To Store

  1. Write down the date on a masking tape and put it on a jar. Place the miso in a dark and cool place for at least 3 months (I put in a storage underneath the stairs). You can also use a dark pillow case and try to find a darker spot in the house.
    Homemade Miso 22

After 3 Months (April/May)

  1. Stir the miso from the bottom up once a month to avoid mold forming. When checking the miso, do so quickly to avoid exposure to air. If you see any mold on the surface, carefully scrape it off. Clean the inside surface walls of the container with a shochu-soaked cloth to deter mold. Smooth the surface, place a new plastic wrap on top, and put the weight back on top. Place the container back to a dark and cool place for another 3 months.

After 3 More Months (July/August)

  1. During summer months, the fermentation will be faster but the chances of getting mold are higher. Stir the miso from the bottom up every 2-3 weeks and check your jar regularly and remove any mold appearing on the surface. Even if a layer of mold covers the entire surface, the miso below should be fine. Just scrape off the surface to a sufficient depth where only mold free miso can be seen. Clean the inside surface walls of the container with a shochu-soaked cloth to deter mold. Smooth the surface, place a new plastic wrap on top, and put the weight back on top. Place the container back to a dark and cool place for one more month.

When Miso is Done (September)…

  1. Remove the weights once the miso is done and store it in the refrigerator to prevent from over-fermenting. You can divide the miso into smaller containers so they will fit in your refrigerator. Now you can enjoy your own miso paste made with patience, love, and perseverance. 

Recipe Notes

This miso recipe is based on this Japanese miso company's tutorial. Please understand that this recipe is work in progress. I will be updating accordingly.


Rice koji: You can buy rice koji from Anything from Japan, Amazon, or Japanese grocery store (you can find Cold Mountain brand and other brands).


Soybeans: 1 cup of dry soybeans is 180 g.


Recipe by Namiko Chen of Just One Cookbook. All images and content on this site are copyright protected. Please do not use my images without my permission. If you’d like to share this recipe on your site, please re-write the recipe in your own words and link to this post as the original source. Thank you.