The day before you make the miso, rinse the soy beans well and soak in plenty of water. The soy beans will swell up to several times their original size, so soak them in a large container.

Put the soy beans and a bit more water than the soy beans in a pot and bring to a boil.

If cooking in a pressure cooker: Divide the soy beans into amounts that can be cooked in your pressure cooker, and cook them in several batches. Put a small lid that sits on top of the beans inside the cooker (a drop lid or otoshibuta) and cook under pressure for 15 minutes. Let it cool down naturally.

If cooking the beans in a regular pot: Simmer over low heat for about 2 hours.

When the soy beans are soft enough to mash between your fingers, drain them into a colander, leaving 1 cup (200 ml) of the cooking liquid in reserve.

When the soy beans have cooled down to about body temperature, add the salted rice malt, and mix it all up. Try not to crush the rice malt.

If you mashed up the beans in a bag, just add the rice malt to the bag and mix.

Add the reserved cooking liquid, little by little, until the mixture holds its shape when you press it into a ball with your hands.

If the mixture is too moist, it will mold easily, so be careful. About 1/2-2/3rds cup (100-130 ml or so) of liquid should be enough.

Wash a resealable container or tub (there are cheap large tubs for making pickles for sale in Japan, which are perfect), let it dry, then sterilize it with white liquor or any other high-alcohol content liquor (like vodka).

Use a double layer of large plastic bags, and put it inside the tub.

Form the soy bean mixture into fist-sized balls, and slam the balls into the tub. Throw them as hard as you can to release any air pockets. Any air would cause the miso to mold!

Wipe any soy beans from the sides of the tub with a paper towel soaked in alcohol as completely as possible. Press a piece of plastic wrap tightly on the surface of the miso, and seal up the plastic bag.

Lastly, put the tub in a plastic bag so that dust doesn't get inside.

Store the tub in a warm place in the winter, and in the spring, store it in the coolest place in the house.

Cover the surface with plastic wrap, put the tub in a plastic bag and tie it up. If there is no liquid on top of the miso, reduce the weight by 1/2. If there is liquid on the surface, remove the weight.

If any miso gets on the lid or the rim of the tub, wipe it off with alcohol. In the summer months, some mold may grow, in which case just scrape it off and add salt to where the mold was growing.

Check it once in a while to see if any mold has grown. Otherwise, just leave it alone. It will be ready to eat in October to November (if you make it at the beginning of the year). Aim to eat it up within a year.