Shoyu Recipe

Prep kombu and shiitake

Wipe the kombu lightly with a damp cloth to remove any grit (do not wash under running water). Rinse the dried shiitake briefly and set aside to add to the pot.

Combine liquids and aromatics

In a small saucepan combine light soy sauce, dark soy sauce, mirin, sake and 1/2 cup water. Add the kombu piece, dried shiitake mushrooms, crushed garlic, sliced ginger, and scallion pieces.

Slow heat for infusion

Place the saucepan over low heat and slowly warm the mixture. Heat gently until just below a simmer (small bubbles around edge) — do not boil, especially while kombu is in the liquid, to avoid bitterness. Maintain this temperature for 10 minutes to allow flavors to begin infusing.

Remove kombu and continue

Remove the kombu after 10 minutes. Bring the mixture up to a gentle simmer for 2–3 minutes to extract more flavor from the shiitake and aromatics, then turn off the heat.

Steep with katsuobushi

Add the 1/2 cup katsuobushi (dried bonito flakes) to the hot but off-heat mixture. Let it steep for 5 minutes, gently pressing the flakes with a spoon to release flavor.

Strain

Line a fine-mesh sieve with cheesecloth (or use a fine sieve) and strain the entire mixture into a heatproof bowl or measuring cup, pressing gently on solids to extract liquid but not forcing through sediment. Discard solids (kombu, mushrooms, garlic, ginger, scallion, and bonito flakes).

Adjust sweetness and seasoning

Taste the strained shoyu. If desired for balance, stir in up to 1 teaspoon granulated sugar and/or 1 teaspoon honey or maple syrup, tasting after each addition. The final sauce should be savory with a hint of sweetness and rounded umami — adjust in small increments.

Cool and store

Allow the shoyu to cool to room temperature. Transfer to a clean jar or bottle, seal, and refrigerate. Use within 2–4 weeks for best flavor. Shake or stir before using if any sediment forms.

This shoyu is a versatile seasoned soy sauce suitable for finishing ramen, marinades, dipping sauces, or dressings. If you need a lighter table soy, dilute 1 part prepared shoyu with 1–2 parts water. For a stronger broth base, use undiluted.