Wash the dry soybeans under running water until the water become clear.
Soak the washed dry soybeans for over 18 hours
After over 18 hours have passed, drain the water and place the soaked soybeans in a pressure cooker. *1
Add enough water to cover the soybeans, lock on the lid in place and select pressure cooker. *2
Set the timer to pressure cook for 5 minutes. When the 5 minutes is up, let the pressure come down naturally.
While the soybean is being cooked, place salt and koji in a mixing bowl and combine them well and set aside.
Pick one bean and check if you can squish the bean with your finger tips. If it can be squished, it is the right softness to mash.
Mash the cooked soybean. I used a stand mixer with a mincer attachment, but if you don't have it, just use a potato masher and mash them finely.
Place the mashed soybean in a large mixing bowl while it is still hot and add koji and salt to the bowl. *3
Mix them well with your hands and add some liquid if necessary. I add about 1/2 cup of liquid.
Make the mashed soybeans into baseball sized balls.
Slam the mashed soybean mixture balls into a container that is going to be used for fermenting 2-3 balls at a time and press them compactly in order to let any air bubbles out. Repeat the process until all soybean balls are compressed into the container.
Smoothe the surface and wipe off any soybean mash from the container.
Sprinkle salt to cover the surface.
Place 20% of the mixtures weight over the salt sprinkled surface. I used salt in a ziplock bag. *4
Cover the container with cling wrap and place a lid.
Store the container in dark and cool place for at least 3 months. Write the date prepared on the lid.
After 3 months, open the lid, remove the weight and turn the mixture with an wooden spatula.
Smooth the surface again and place a cling wrap on top.
Place the container back to a dark and cool place for another 2-3 months.
After 2-3 months, transfer the container to a cooler place like the fridge in order to stop the Miso from over fermenting. *5
*1. I used an InstaPot. If you don't have any pressure cooker, add water just enough to cover the soybean. Bring it to boil and then turn the heat down and simmer for 3-4 hours. *2. I add 3 cups of water to cook.*3. The soybeans need to be mashed while they are still hot, but make sure when you add the koji, the mashed soybean temperature is below 40°C(104°F), above 65°C(149°F) will kill koji. *4. This recipe will make about 1 kg of Miso so the 20% weight is about 200g. *5. I empty and transfer the miso to a different container to keep in my fridge as the fermenting container was big. If you have enough space in your fridge, you don't need to replace the container. *6. Shochu is typically used in Japan. It is quite expensive outside of Japan, Vodka can be used alternatively, or I used Dover pasteuriser 77.