How to Make Miso. Miso is a Japanese condiment that is made from soybeans. The soybeans are mixed together and processed into a red, yellow or white paste. It is combined with rice, then fermented for one to three years. After the fermentation process, the miso can be added to soups, sauces, ramen noodles, dressings and marinades.
Soak the soybeans in a bowl of water. Keep them in water for 3 hours. The soybeans should expand in size.
Add the soaked soybeans with the water into a pressure cooker. Cook the soybeans for 40 minutes until they are softened. Drain the soybeans into a bowl by using a colander.
Puree the beans with a potato masher. Mash the soybeans while they're still hot so that they can easily become a paste. Let the soybeans cool down before adding the koji rice.
Dissolve some of the salt in one cup of water, but set aside two teaspoons of the salt for later. Stir the salt water mixture into the mashed soybeans, adding more as needed. Sprinkle the koji rice onto the miso. Mix everything with your hands until the texture becomes smooth.
Find a cylindrical-shaped ceramic container that can be used for food. If necessary, shop for the container at a kitchen supply store. Add about one teaspoon of salt around the inside of the container, then add the miso. The miso can spoil easily when exposed to air, so add another teaspoon of salt to preserve it.
Cover the miso with plastic wrap or a paper towel before placing it in the container. Then, put some weights into the container, such as small washed stones, followed by a wooden lid to cover the miso.
Use some wrapping paper along with a string to cover the ceramic container with the miso inside. Place the container in an open space with a room temperature of around 60 degrees F so that the miso starts to ferment.