Mentsuyu Concentrate (Dashi to Soy to Mirin)

1 part

Koikuchi soy sauce (dark) — Standard Japanese dark soy; tamari for gluten-free

1 part

Mirin (hon-mirin) — Must be hon-mirin (real fermented mirin), not mirin-style seasoning — the alcohol and natural sugars matter

4 parts

Ichiban dashi — Katsuobushi-kombu first-draw dashi; dried sardine (niboshi) dashi for a more robust concentrate

0.5 parts

Sake (optional) — Added with mirin; burned off by simmering to mellow the raw alcohol edge

Combine mirin and sake in a small saucepan over medium heat. Bring to a simmer and flambe or cook for 2 minutes to burn off raw alcohol. Add soy sauce and dashi. Return to a gentle simmer for 3–5 minutes — do not boil hard, which drives off katsuobushi aromatics. Cool completely. Store refrigerated up to 2 weeks. To serve: dilute with warm water (hot broth) or cold water (dipping sauce) at the ratios below, then garnish with grated daikon, yuzu zest, or sliced negi.

• Always use hon-mirin — it contains actual alcohol and fermented sugars that contribute sweetness and umami; mirin-style seasoning (aji-mirin) is corn syrup and will produce a cloying, flat concentrate.
• Burn off mirin alcohol before adding dashi: raw alcohol vapor can taste harsh in a finished tsuyu.
• Cold noodles need a stronger dipping sauce because cold temperatures suppress perceived saltiness and sweetness — the 1:3 dilution accounts for this.
• Taste the dashi before building concentrate; inferior dashi produces inferior tsuyu regardless of ratios.
• Aged mentsuyu (3–5 days in the refrigerator) is noticeably smoother than freshly made — allow time for flavors to meld.
• The soy-to-mirin 1:1 ratio is the classic Kanto (Tokyo) style; Kansai (Osaka/Kyoto) preparations use lighter usukuchi soy and may pull back mirin slightly for a paler, milder concentrate.

• Zaru soba dipping sauce (tsuke-tsuyu)

  Dilute concentrate 1:3 with cold water; served icy cold alongside cold soba noodles

• Kake broth (kakejiru)

  Dilute concentrate 1:7 with hot dashi for a light soup noodle broth; season with salt to taste

• Tempura dipping sauce (tentsuyu)

  Concentrate diluted 1:2 with dashi, served hot; garnish with grated daikon and ginger

• Niboshi tsuyu

  Replace katsuobushi dashi with dried sardine dashi; dominant in eastern Japan (Kanto) for a fishier, more pungent concentrate

• Oyakodon sauce

  Same concentrate diluted lightly (1:4) and used to braise chicken and onions for oyakodon rice bowls

• Dashimaki tamago seasoning

  Thinned concentrate (1 tbsp per 3 eggs) folded into the egg mixture for Japanese rolled omelette

• Miso Soup (Dashi to Miso)

  Shares the same ichiban dashi base; contrasts the soy-forward vs miso-forward flavor axis

• Teriyaki Glaze (Soy to Mirin to Sake)

  Same core trio (soy, mirin, sake) reduced to a glaze rather than diluted for broth

• Ichiban Dashi (Kombu to Katsuobushi)

  The foundation stock; its quality directly determines tsuyu quality

1. 1.Japanese Farm Food — Nancy Singleton Hachisu
2. 2.The Zen Monastery Cookbook — Dogen Zenji (traditional tsuyu methods)
3. 3.Japanese Soul Cooking — Tadashi Ono & Harris Salat
4. 4.Nobu: The Cookbook — Nobu Matsuhisa (on dilution logic for dipping vs broth)

Confidence: high