Stocks & broths
awase dashi
合わせ出汁 · A clean, high-clarity stock built from kombu (dried kelp) and katsuobushi (dried, fermented, smoked skipjack tuna), producing the characteristic savory depth called umami. It is the foundational broth of Japanese cooking — the liquid upon which miso soup, noodle broths, simmered dishes, and many sauces rest.
The formula
15 g kombu : 8 g katsuobushi : 1 L cold water (≈2 : 1 by weight)
The classical shoin (basic) ratio. Reduce kombu to 10 g for a lighter, subtler stock; increase katsuobushi to 12 g for a stronger bonito presence. The ratio of kombu to katsuobushi by weight is roughly 2:1. Never boil the kombu — simmering extracts bitter mucilage. Bring kombu to just below boiling, remove it, then steep katsuobushi off-heat.
Identity
- Kombu is simmered cold-to-warm, never boiled — boiling extracts bitter polysaccharide mucilage
- Katsuobushi is steeped off-heat after kombu is removed — heat destroys the delicate inosine
- Dashi must be strained through cloth and used the same day for the clearest, most fragrant result
- No salt, no seasoning added — the stock is used as-is and seasoned at the dish level
- The two ingredients are complementary: kombu provides glutamates; katsuobushi provides inosinates — together they produce synergistic umami multiplication
Ingredients
| Liquid | water | Use filtered or soft water; hard mineral water overwhelms the delicate aromatics. Tap water with chlorine imparts off-flavors — let it rest overnight or use filtered. |
| Base | kombu (dried kelp, Saccharina japonica) | Wipe with a damp cloth; do not scrub or soak before cooking. The white powder on the surface is beneficial natural glutamate. Use grade-appropriate kombu: ma-kombu for everyday use, rausu-kombu for premium. 15–20 g per liter. |
| Base | katsuobushi (dried, fermented, smoked skipjack tuna) | Honthsu-grade or higher. The bonito flakes left after steeping are used for garnish or as a condiment; the umami-rich infusion remains in the liquid. 8–10 g per liter. |
Method
- 1Combine water and kombu in a heavy pot (stainless steel or enamel). Cover and refrigerate for 30 minutes to 12 hours (optionally overnight for deeper extraction).Cold extraction draws glutamates slowly from the kombu without bitter mucilage. A long cold soak at low temperature is gentler and more controlled than direct heating.
- 2Place the pot over medium-low heat. Bring to a bare simmer — just before the first bubbles break the surface (85–90 °C). Foam may form; skim lightly. The kombu will feel soft and slightly slimy.Heating too fast or to a boil forces bitter polysaccharides out of the kombu. The target is maximum glutamate extraction with zero bitterness. Gentle heat is non-negotiable.
- 3Remove the kombu the instant the first bubbles appear. Reserve the kombu (it can be sliced thin and used in simmered dishes, salads, or as a second-stock ingredient).Boiling kombu for even 30 seconds extracts astringent mucilage and produces a cloudy, bitter stock. The removal point is critical — watch the pot.
- 4Bring the remaining liquid to a full boil. Remove from heat. Add katsuobushi, stir once, and steep for 3–5 minutes without stirring again.A brief full boil sanitizes and opens the bonito's cell structure; steeping off-heat extracts inosinates gently. Reheating or agitation after adding bonito clouds the stock and mutes flavor.
- 5Strain through a fine-mesh strainer lined with dampened cheesecloth or a paper coffee filter. Do not press the bonito flakes.Pressing squeezes out bitter, cloudy liquid trapped between flakes. Light straining yields a crystal-clear, amber-gold broth with a clean, oceanic aroma.
Techniques that matter
Temperature-controlled extraction
Kombu glutamates extract best below 90 °C; katsuobushi inosinates extract best in a brief boil followed by steep. Using two temperatures in sequence maximizes both savory components.
Cloth straining
Fine-mesh alone is insufficient; cheesecloth or paper filtration removes even sub-micron particulate that would cloud the broth and impart off-flavors during storage.
Cold-soak method
Soaking kombu in cold water for 30 min to 12 h extracts glutamates without heat — the safest, most forgiving approach for consistent results at any skill level.
Variations & derivatives
Hokkaido dashiHokkaido, Japan
Adds nibun-katsuobushi (dried sardine/anchovy flakes) at 3–5 g per liter alongside the standard bonito, producing a deeper, more oceanic stock used in miso ramen bases.
Shirodashi (light dashi)Kanto region
Kombu is omitted or halved; the ratio shifts to 5 g kombu : 12 g katsuobushi per liter, producing a paler, bonito-forward broth used for clear soups (suimono) where color matters.
Awase dashi with dried shiitakeKansai / Buddhist cuisine
Adds 1–2 dried shiitake mushrooms (steeped separately and added) for a vegan or vegetarian umami stock called kombu-shiitake dashi. The shiitake contribute guanylate; kombu contributes glutamate — another synergistic pair.
Ebi dashi (prawn-shell dashi)Japanese nouvelle / tempura broths
Adds prawn shells roasted dry and simmered briefly for a crustacean note; still uses kombu as the backbone. Used in some regional ramen and premium chawanmushi.
Awase dashi with sardines (iwashi)Shikoku / Kyushu
Replaces or supplements katsuobushi with dried sardines (areng), producing a bolder, fishier stock typical of miso soup in southern Japan.
Used in these dishes
Substitutions
- katsuobushi → hondashi (granulated bonito seasoning) — Granulated hondashi is a concentrated, salt-seasoned bonito extract. It provides umami but lacks the aromatic depth and clarity of real steeped katsuobushi. Use 1–2 g per liter and omit salt in the finished dish. Not interchangeable for a truly classical preparation.changes result
- kombu → kombu powder or kombu extract — Provides glutamate but lacks the structural integrity for proper extraction technique. A last resort only — adjust ratio to taste and expect a less nuanced result.changes result
- both ingredients → dashi powder (hon-dashi) — Pre-packaged hon-dashi contains salt, MSG, and bonito extract. It will season and provide umami but cannot replicate the clarity, aroma, or technique-based extraction of real awase dashi.changes result
Troubleshooting
Stock is cloudy
Kombu was boiled rather than simmered, or bonito was pressed during straining, or heat was too high at any stage → Start over. Strain through cheesecloth on a second pass. Going forward, never exceed 90 °C with kombu in the pot.
Stock tastes bitter, grassy, or harsh
Kombu was cooked past the first bubble; the mucilage compounds were extracted. Also caused by using old, oxidized kombu. → Remove kombu earlier — before any bubbling. Use fresher kombu. The bitterness cannot be removed once extracted; begin a new batch.
Stock has no umami depth — tastes flat and watery
Kombu is too old (glutamate depleted), ratio is too low, or cold-soak time was insufficient. Bonito was not steeped long enough. → Use younger, properly stored kombu (refrigerate after opening). Steep bonito for the full 5 minutes. Consider a longer cold soak for the kombu (up to 12 hours).
Off smell — sour, fishy, or 'tinny'
Katsuobushi was stored improperly (exposed to air, light, or humidity) or was past shelf life; bonito oxidizes quickly once ground → Store katsuobushi in an airtight container in the refrigerator or freezer. Use within 2–3 weeks of opening. Smell the bonito before use — it should smell intensely smoky-sweet, not stale or sour.