Natto Recipe – Japanese Fermented Soybean

This unconventional ferment is infamous for its piquant aroma and sticky texture. It’s treated as a medicinal food and is often served with rice and hot mustard for breakfast.

Preparation Time: 4 hours                             Fermentation Time: 24 hours

For your first batch, you’ll need to buy prepared natto from a store and after that, you can save a small amount of homemade natto in your freezer and use it to start your next batch.


  • 1 cup of dry soybeans (soaked in the water for 6 to 10 hours and drained)
  • 3 cups of water
  • 1 package of plain natto
  • 2 tablespoons of hot water
  • 2 1l jars
  • A few bottles for hot water
  • Small cooler

How To Make It?

  1. Steam your cooked but intact soybeans for 2 to 4 hours in a steamer basket, or until they just smash when pinched.
  2. In a small bowl, mix 5 to 6 beans from the premade natto with hot water then add to the previously cooked soybeans and mix them all thoroughly.
  3. Transfer inoculated soybeans to your two 1l jars. Cover the mouth parts of each jar with fabric and tighten with a rubber band.
  4. Heat your small cooler by rinsing the inside with hot water. Place the jars in the cooler along with a few bottles of hot water (about 120°F or 49°C).
  5. Cover the jars and water bottles with a fabric or towel and close cooler. After 12 hours, replenish the hot water in the jars and then ferment for another 12 hours.
  6. Your homemade natto is ready when a moldy film has developed on the soybeans and a fibrous texture is formed when you stir them. Be careful! Because natto will also smell strongly of ammonia.
  7. Cover firmly and refrigerate for 2 to 3 days to allow the smell of ammonia to dissipate. You can keep your natto refrigerated for several weeks and you can freeze it for longer storage.

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