Homemade Miso Cold-Brewing (Adventure Edition)

The Great Cold (Daikan) of 2025 is January 20th.
It is said that the period from then until Setsubun on February 2nd is considered the 'Great Cold Period'.

It feels relatively warm this year, but
the mornings and evenings are still chilly and the wind is cold, so
I've been spending a lot of time cozy at home lately.

However, now that the cold is severe,
it is the perfect time to make homemade miso!

By putting in the effort to prepare it,
you can enjoy the deep flavor unique to homemade miso in half a year.

In our home, we tried making miso once last year,
and we were able to make delicious miso.

This year is our second attempt.

I read various articles on how to make it,
scoured YouTube,
and combined methods that seemed good and easy,
so I tried making miso in my own way,

and I'd like to summarize that process here!

Going original in my second year is reckless...
I'll pretend I didn't hear that. lol

Reasons and points for recommending cold-brewing miso

Miso made during the cold season
has long been called 'cold-brewing'.

Miso can be made throughout the year, but
cold-brewed miso is characterized by
being made during the cold winter season,
which allows fermentation to proceed slowly,
creating a deep umami and mellow flavor.

Here, I will summarize the reasons why cold-brewing is recommended and its key points.

1. Low-temperature fermentation suppresses the growth of unwanted bacteria

Because the temperature is low in winter, the growth of unwanted bacteria, which are the greatest enemy of miso making, is suppressed.
In particular, the period immediately after preparation is when bacteria are most likely to enter, so you can prepare it with peace of mind in a cold environment.

2. Koji activity is stabilized, and fermentation proceeds slowly

When made in the cold season, the activity of the koji mold becomes gentle, and fermentation proceeds slowly.
This slow fermentation is important for deepening the umami and aroma of the miso.

3. The flavor finishes mellow

Miso that has been aged slowly loses its saltiness and becomes mellow in flavor.
When aged over a long period, the sweetness and richness increase, resulting in a well-balanced flavor.

4. Miso is easier to manage

Cold-brewing is easier to manage because fermentation does not progress rapidly as it does in warmer seasons.
The risk of mold is also reduced, so you can wait for it to age with peace of mind.

5. Fresh ingredients are available

The main ingredients, soybeans and koji (rice), are harvested in the autumn, so it is recommended to prepare it around winter when new soybeans become available.
New beans harvested shortly before have a high moisture content and can be boiled until soft, making them suitable for miso making.

Let's! Make Miso

Ingredients

• Dried soybeans: 600g

• Dried rice koji: 600g

• Natural salt: 300g

• Sake lees

Note: The soybeans used this time were ones I had stored at home for emergencies.
The expiration date had passed in October 2024... ^^;
The flavor might be slightly diminished, but since they seemed fine to use,
I'm proceeding with making miso at my own risk!
I'm taking on the challenge of seeing if I can make miso with old beans☆

Preparation the Day Before

1. Wash the soybeans thoroughly.

Even if soybeans look clean, they can sometimes be dirty.
Since dirt can negatively affect the miso-making process, wash them by rubbing the beans against each other, similar to how you would wash rice.
The goal is to wash them until the water runs clear.
Usually, the water becomes clear after about three rinses.

2. Soak in water for 18 hours.

If the water temperature is cold (around 10°C), you will need to soak them for at least 18 hours.
Make sure to soak the dried soybeans in at least three times their weight in water.
If the soybeans haven't absorbed enough water, they won't cook properly.
Be sure to take your time and let them soak thoroughly.

Process on the Day Of

1. Boil the soybeans.

Once you have confirmed that the soybeans have absorbed enough water, replace it with fresh water and put them into a large pot.
The water level in the pot should be enough to cover all the beans,just enough to cover them,cook over medium heatfor2 to 3 hours until they are soft enough to be easily crushed with your fingers.

Note: You can also use apressure cookerto boil the soybeans.
If using a pressure cooker,cook on low to medium heat for 15 minutesunder pressure, then turn off the heat and let it cool naturally. Check the softness of the beans, and if they are still hard, boil them a bit longer.

2. Mix the koji and salt.

Put the dried rice koji and salt into a large bowl and rub them together well with your hands to make "salt-mixed koji." Mix thoroughly so that everything is evenly distributed.

3. Crush the soybeans.

Soybeans are easier to crush while hot, so once they are boiled, use a food processor, mortar and pestle, or rolling pin to crush them.
A food processor is recommended if you have a large quantity of beans or want to save time.
This time, I used a food processor briefly and then crushed them further with a rolling pin.

* This time, some grains remained and there were parts that were hard to crush, which might be because the beans were old.
New beans are said to boil softer and are easier to crush, so if you want to make smooth miso, I recommend using new beans.😂

④ Mix the koji and salt mixture with the crushed soybeans.

Let the crushed soybeans cool to body temperature (about 30 degrees Celsius), and combine with the salt-mixed koji.
Mix well while crushing and squeezing together with your hands.

⑤ Add the boiling liquid to the mixed soybeans to adjust the consistency.

Add the cooled soybean boiling liquid little by little, and mix evenly about 60 times by scooping from the bottom and pressing down from the top.
Incorporate it thoroughly, and adjust the consistency by adding the liquid until it feels a little softer than an earlobe.

⑥ Pack into a container.

This time, I will age the miso using a special container called "Iki-Iki Pail".

Take the miso base in your hand and put it into the container as if slapping it in.

If miso comes into contact with air while fermenting, mold will grow from there, so usually, you squeeze miso balls tightly and slap them in to prevent air from entering.
However, even without making miso balls, if you make it slightly softer, you can pack it so that no air enters.

To firmly remove air, let's push it down with our fists several times along the way.

⑦ Cover with sake lees.

Finally, I will put on a lid to prevent mold.
I saw information that mold is less likely to grow if you cover it with sake lees, so I decided to try that method this time.

First, just in case, I sprinkled a little salt on the surface.
Next, since I didn't want the sake lees to mix with the miso, I laid down a non-woven fabric and spread the sake lees densely on top of it.

If there is any excess miso or dirt on the inside of the bucket, it will cause spoilage, so let's wipe it off thoroughly with alcohol.

Finally, cover with plastic wrap, put the bucket lid on, and the preparation is complete.

⑧ Let it rest in a cool, dark place for about half a year.
It has some height so it should be fine, but
just in case, I will wrap the bucket in newspaper
and store it in a relatively cool place in the house.

I wonder how it will turn out in half a year?
I plan to share how it looks when I open it
later on, so please look forward to it♪

Finally

How was it?

Using old beans,
packing them in without making miso balls,
using a mysterious container called an Iki-Iki Pail,
covering it with sake lees instead of salt,
and not using a weight...

It feels like I'm taking quite a few risks, but
believing that delicious miso will be made safely,
I will wait for half a year😂

The results will be a surprise in half a year♪

※ Just in case it fails,
I'm also thinking about making a safe batch of miso with new beans... Haha

🍀🍀🍀🍀↓2025.9.3 Update↓🍀🍀🍀🍀
I meant to mix it halfway through, but I completely forgot, and 7 months have already passed.
Just as I ran out of miso, I decided to open it with a pounding heart!

.
.
.

Oh! There's absolutely no mold at all✨✨
Thanks to the sake lees?!
(I forgot to take a picture, but the sake lees I used as a lid had also turned brownish.)
It's a little uneven, but once mixed, the fermentation level is just right♪

It feels a little grainy and maybe a bit light (perhaps because they were old soybeans?), but overall it doesn't bother me at all!
Delicious miso has been made👏

I still have some old soybeans in storage, but using this method for miso is definitely an option💛
Maybe I'll make a bit more next year!

Everyone, please feel free to use this as a reference✨

Thank you for reading until the end.
Likes and follows are encouraging!
Please support me♪