Fermented soy beans with a funky aroma and earthy flavor! While often served with a bowl of rice, soy sauce, spicy mustard and an egg; try mixing it with just about any grain and condiment for a fast, highly nutritious, protein-rich and satisfying meal.
Rinse the soybeans and soak for 9-12 hours (longer soaking time recommended in winter months) at a ratio of 3 parts water to 1 part soybeans. Drain the beans in a colander or sieve. Fill a large pot with fresh water and simmer for about 9 hours. (If using a pressure cooker or Instant Pot, follow manufacturer’s instructions for cooking beans).
Drain the cooked beans and return them to the pot. Dissolve the culture into 1 Tablespoon of pre-boiled water (to sterilize). Immediately pour the natto spore solution you just made over the beans while the beans are still hot. (Don’t worry about the hot temperature, the heat activates the cultures). Stir the beans and water mixture thoroughly. Carefully spread in a thin even layer approximately 1/2 - 1” deep in a glass casseroles dish. Stretch aluminum foil across the top of the casserole dish, crimping the edges and sealing tightly. While holding it taut, poke a series of air holes. (Alternatively, you can use several 4 oz glass jars with a layer of muslin over the top of the jars and place a tight-fitting lid on top, in lieu of a baking dish).
Incubate at 100º using our Brod & Taylor Proofer or following another Fermentation Incubation Hack and allow the natto to ferment for 20 -24 hours making sure that the 100ºF temperature is maintained. After 20-24 hours check for slimy film and texture. Ferment a few hours longer if needed, until slimy-film is in full form. After the fermentation period let the natto cool for a couple of hours with the cover still on. Then, the natto can be stored in a sealed container in the refrigerator. Enjoy within about 6 weeks. (Some like to let it age in the fridge for an additional week before eating to develop stronger flavors). Smaller portions can be stored in the freezer and thawed for later use.