The higher ratio of beans to koji, the increased amount of salt, and the longer fermentation period make this a darker, saltier, stronger-tasting miso.
- 3 cups soybeans
- 1/2 cup barley koji
- 7 tablespoons salt, plus
- 1 teaspoon extra to sprinkle on surface
- 2 cups water (save this from the cooked beans)
- 1 tablespoon unpasteurized miso (optional)
- Soak the soybeans for 12 to 18 hours, then rinse, cover with fresh water, bring to the boil, then reduce to a low heat and simmer gently until soft — around 3 to 4 hours.
- Drain, reserving the cooking liquid, then mash the beans. Keep some chunkier pieces for a rougher texture, or mash to a pulp for a smoother miso.
- Leave to cool to room temperature. If the koji is added while the beans are hot, the beneficial mold will be killed. The mold is the culture which aids the fermentation process and transforms the mashed beans into miso, and it’s the by-products of the mold fermentation that give miso its health benefits.
- Stir the koji and salt together. Add the tablespoon of miso, if using, to the salt and koji. This helps start fermentation. Then mix both salt, koji, and optional miso into the mashed soybeans.
- Add some of the reserved cooking liquid, a little at a time, to loosen the mixture. Aim for the consistency of mashed potatoes.
- Spoon mash into a clean, wide-mouthed glass or ceramic vessel. Press out all of the air as you fill the jar to eliminate oxygen, which can cause unwanted bacteria or molds to grow. If you’re careful, this shouldn’t be a problem. The salt in the miso and the proliferation of lactic acid bacteria and molds will inhibit any other growth.
- Sprinkle the surface of the miso with a final teaspoonful of salt, then put a piece of plastic wrap directly onto the surface to keep out air. Place a weight, such as a glass pickle weight or a flat stone, on top of the plastic wrap. Put a final cover of a muslin cloth or a lid over the jar. If using a lid, remember that microbial action means gas will be given off, so it needs to be loosely fitting or have a vent in the top.
- Place the jar somewhere dark with an even temperature, such as a closet away from heating.
- Check every 4 weeks for unwanted mold on the miso’s surface. If there’s white mold growth, it’s harmless; scrape it away and clean the sides of the jar. Then top miso with fresh salt, new plastic wrap, and a clean weight.
- Ferment this miso for around a year. It may be ready in less if it ferments over the summer months, as this season boosts bacterial activity. Start tasting it after 9 or 10 months. Once the flavor has developed, it can be transferred to the refrigerator.
Learn more about this unassuming superfood in The Health Benefits and Uses of Miso
Enjoy creating your own miso and using both light and dark versions in tasty, healthful dishes.
Claire Jones is a freelance writer specializing in natural health and sustainability. She is a vegetarian, grows her own fruits and vegetables, and likes experimenting with fermentation.