Homemade Miso

Miso is one of the cornerstones of Japanese cuisine, a protein rich paste of fermented soy beans used in making pickles, sauces, spreads and in its most well known guise as soup.  Here in the middle of the UK it is pretty difficult to get hold of good miso, and when you find it you can end up paying luxury prices for a basic ingredient, so, having some home-brewing experience we decided to try making our own.  A fungus called koji is grown on grains such as rice or barley before being introduced to cooked beans and salt.  The salt kills off any bacteria present to make an environment conducive to fermenting, but since the koji enzymes can still function in a salty environment, they continue to do their job breaking down the carbohydrates and proteins creating the paste we know and love.

The process of making your own miso isn’t a short one, taking around two months to get a usable product, but we feel that following the journey from beans to miso is helpful in understanding Japanese food.  Rice grains inoculated with koji can be bought online from a number of suppliers, otherwise all the ingredients are extremely easy to get and the hardest part of the procedure is the waiting and resisting using your paste before it’s ready.  Incidentally, you also end up with a small amount of home-brewed tamari every now and then as it leaches out of the miso.  We wouldn’t have been able to work out how to make miso without the help of the brilliant, but out of print, Book of Miso by William Shurtleff & Akiko Aoyagi; we highly recommend hunting down a copy if you want to experiment some more with fermenting your own miso.

Homemade Miso



  • 2 cups dried soy beans
  • 2.5 cups genmai (brown rice) koji, we used Terrasana brand
  • 4.5 tablespoons sea salt


  1. Put the dried soy beans in a bowl, cover with plenty of water, and leave to soak for 12 hours until they’ve doubled in size.  Once they’ve soaked, drain off the soaking water, and place in a large pan with clean water.  Put a lid on the pan and bring to a boil, then reduce the heat to low and simmer for 4 1/2 to 5 hours, skimming any foam off the surface of the beans as they cook.  You’ll need to add extra boiling water as necessary- the beans need space to cook properly, and you need to make sure you end up with at least 3 cups of cooking liquid left over, to use for mixing your miso.  If you have a pressure cooker, you can cook the beans with 5 cups of water at high pressure for 3 hours.
  2. Once they are soft, place a colander over a bowl and drain the beans, reserving the cooking liquid for use later.  Making sure your hands and any kitchen utensils used are very clean, return the beans to the pan and mash them with a potato masher.  If you’d like a chunkier textured miso, leave some beans whole, but we prefer ours smooth so we mashed all the beans to a paste.  Allow the bean paste to cool to below 43ºC, otherwise the heat will kill the koji spores.
  3. Add the sea salt to 3 cups of the reserved bean cooking liquid, and stir to dissolve.  Pour this over the mashed bean paste and mix well.  Now add the dried genmai koji, and fold the grains into the paste with your hands, making sure all ingredients are thoroughly combined.  After it has been mixed, your paste should have the consistency of regular, shop bought miso.
  4. Prepare your fermenting vessel by making sure it is clean and dried well (we used a 2L tempered glass container with a snap-fit plastic lid, made by Glasslock).  Now, sprinkle half a teaspoon of salt over the sides and base of the container and spoon in your miso, making sure to press it down firmly so no air pockets are present.  Smooth the top of the miso, then sprinkle a teaspoon of salt over the surface.  Put the lid on the fermenting container, wrap with towels to help the mixture stay warm and keep light out, and put this bundle in a warm place to ferment- we kept ours on top of the refrigerator, leaving it in an airing cupboard would be perfect.
  5. Make a note of the date you started the miso, and leave it undisturbed for 2 weeks.  The first time you check on it, you should remove any surface mould that may be present, and give it a good stir to make sure fermentation is occurring evenly.  Re-wrap the miso, and check on it in this way every 2 weeks, leaving it to ferment for a total of 8 weeks, before putting the container into the fridge.  The cooler temperature will slow fermentation drastically, but not stop it completely- unpasteurised miso is a living food, and it is this which gives it its health and flavour benefits. As soon as you move your miso to the fridge it is ready to enjoy!


If you want a completely smooth miso, you can put the finished paste through a blender to get rid of any residual lumps.  Our recipe produces a mild, sweet, pale miso similar to commercial shiro-miso, and can be used as such in any recipe that calls for it.



3 thoughts on “Homemade Miso

  1. Oh my gosh, that’s so amazing that you’re making your own miso at home. I’ve made natto a few times before, but miso sounds like such a complex process. True dedication haha
    Right now I’m making “tofu you” (豆腐よう)at home, but it needs to sit for at least ten days. Have you ever tried it?

    Liked by 1 person

    1. Hehe, it was fairly straightforward to make really- the hardest part was waiting 2 months to taste it. 🙂

      Well done on making your own natto too- natto scares us slightly (we’re ashamed to admit!), so we’ve never actually tried it- it seems like it’d be very very strong tasting due to the stringy texture! We’ll have to be brave next time we visit Japan 😀 Nope, we’ve never tried tofu you; how do you make it? Fermenting is fun!


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