📝 About This Recipe
True Japanese Shoyu is a masterpiece of biological alchemy, born from the patient fermentation of soybeans and toasted wheat. This recipe guides you through the traditional 'Honjozo' method, resulting in a complex, deep-amber liquid that balances salt, sweetness, and an unparalleled savory depth. Crafting your own soy sauce is a transformative culinary journey that connects you to centuries of Japanese tradition and yields a condiment far superior to mass-produced alternatives.
🥗 Ingredients
The Base Legumes and Grains
- 1 kg Organic Whole Soybeans (dried, non-GMO preferred)
- 1 kg Hard Red Winter Wheat (whole berries)
- 4 liters Filtered Water (for soaking and brine)
The Fermentation Starters
- 10 grams Tane Koji (Aspergillus oryzae) (specifically for Shoyu/Soy Sauce)
- 2 tablespoons Rice Flour (to act as a carrier for the spores)
The Brine (Moromi)
- 800 grams High-Quality Sea Salt (non-iodized, such as Kosher or fine sea salt)
- 2.5 liters Spring Water (chlorine-free is essential)
👨🍳 Instructions
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1
Rinse the soybeans thoroughly until the water runs clear. Soak them in 3 liters of filtered water for 12-15 hours; they should double in size and lose their bean-like 'green' smell.
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2
Boil the soaked soybeans in a large pot or pressure cooker. If using a standard pot, simmer for 4-5 hours until the beans are soft enough to be easily crushed between your thumb and pinky finger. Drain well.
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3
While the beans cook, toast the wheat berries in a dry cast-iron skillet over medium heat. Stir constantly for 10-15 minutes until they turn a deep golden brown and smell nutty and fragrant.
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4
Coarsely crack the toasted wheat using a grain mill or a heavy-duty blender. You want large fragments, not a fine flour, to allow for airflow during fermentation.
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5
Spread the warm, drained soybeans and cracked wheat onto a clean tray or bamboo mat (koji-buta). Mix them thoroughly and let the mixture cool to exactly 30°C (86°F).
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6
In a small bowl, mix the Tane Koji spores with the rice flour. Sieve this mixture evenly over the soy-wheat substrate and toss by hand to ensure every grain is inoculated.
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7
Incubate the mixture in a warm, humid environment (approx. 28-30°C) for 48-72 hours. This is the 'Koji' stage. Stir the mixture twice a day to prevent overheating. It is ready when the grains are covered in a fragrant, olive-green mold.
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8
Prepare the brine by dissolving 800g of sea salt into 2.5 liters of spring water. This creates a high-salinity environment that favors beneficial lactic acid bacteria and yeast while inhibiting spoilage.
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9
Combine the finished Koji with the brine in a large food-grade fermentation crock or glass jar. This mixture is now called 'Moromi'.
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10
Cover the container with a breathable cloth and store in a cool, dark place. For the first week, stir the Moromi once a day with a clean wooden paddle. For the next few months, stir once a week.
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11
Allow the Moromi to ferment for at least 6 months, though 12 months is ideal for a complex profile. The liquid will darken from a murky beige to a deep, translucent reddish-brown.
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12
To harvest, line a colander with a heavy-duty nut milk bag or several layers of fine cheesecloth. Pour the Moromi in and let the raw Shoyu drip through naturally for several hours.
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13
Apply pressure to the bag (using weights or a small press) to extract the remaining liquid. The leftover solids (Shoyu-kasu) can be used for pickling vegetables.
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14
Pasteurize the raw shoyu by heating it in a pot to 80°C (176°F) for 20 minutes. This stops fermentation and stabilizes the flavor. Skim off any foam that rises to the surface.
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15
Let the shoyu settle in a tall glass bottle for 2-3 days so any remaining sediment falls to the bottom. Siphon the clear, dark liquid into sterilized bottles for final storage.
💡 Chef's Tips
Temperature control is critical during the Koji stage; if it exceeds 40°C, the spores may die or produce off-flavors. Always use chlorine-free water, as chlorine can inhibit the delicate fermentation process. Ensure all equipment is sterilized with boiling water or high-proof alcohol to prevent harmful mold growth. If the Moromi develops a thin white film on top (kahm yeast), simply skim it off; it is harmless but can affect flavor if left too long. Be patient—the flavor profile drastically shifts from salty and harsh at 3 months to mellow and complex at 12 months.
🍽️ Serving Suggestions
Drizzle over fresh Sashimi or Nigiri to enhance the natural sweetness of the fish. Use as a base for a high-quality Ramen tare by simmering with kombu and mirin. Whisk with toasted sesame oil and grated ginger for an authentic Japanese salad dressing. Pair with a chilled Junmai Ginjo Sake to complement the fermented earthy notes. Brush over grilled Yakitori skewers during the final stages of cooking for a beautiful lacquer finish.