Stocks & broths
ichiban dashi
一番出汁 · The foundational stock of Japanese cuisine, a clear, pale-gold broth of extraordinary umami depth and subtle ocean salinity. Made from two ingredients—dried kelp (kombu) and dried fermented skipjack tuna (katsuobushi)—it is the invisible backbone of miso soup, clear broths, simmered dishes, and noodle sauces across Japanese cooking. It is not boiled; it is infused, and that distinction is the entire point.
The formula
1000 g cold water : 10 g kombu : 20–25 g katsuobushi
The mass-based ratio replaces volume measurements entirely in classical practice. Scale by feel: the finished broth should taste of the sea, not of the seaweed or the fish—it should be the ghost of both.
Identity
- Made with kombu and katsuobushi exclusively—no mirin, no sake, no dried shiitake in this base form
- Infused at sub-simmer temperatures (never boiled) to extract glutamates cleanly without bitterness or cloudiness
- Kombu is removed before adding katsuobushi; the two ingredients are never simmered together
- Strained through fine cloth immediately after steep; never reboiled
- Clear, pale amber, with a clean, oceanic nose and a clean, mineral-umami finish
Ingredients
| Liquid | Cold water | Filtered or soft water preferred; hard mineral water extracts excessive astringency from kombu. Start cold. |
| Base | Kombu (dried Laminaria japonica) | 10 g per liter. Wiped with a damp cloth—never washed. The white powder is glutamates, not dirt. Look for deep forest-green, thick-girthed kombu. Hokkaido rausu-kombu and ma-kombu are the classic grades. |
| Base | Katsuobushi (dried, fermented, smoked skipjack tuna shavings) | 20–25 g per liter. Use block katsuobushi shaved fresh over a grater or plane; pre-shaved loses aroma rapidly. Benizake-grade is standard. Look for pink-amber color with visible fat lines. Store airtight, refrigerated. |
Method
- 1Combine cold water and kombu in a pot. Let soak for at least 30 minutes (up to 12 hours refrigerated). Do not turn on heat yet.Cold soaking slowly hydrates the kombu and begins leaching glutamates into the water without extracting bitter astringent compounds that heat releases from the slimy surface.
- 2Place the pot over medium-low heat. Heat gradually until small bubbles begin to rise from the kombu surface—approximately 60–65 °C (140–150 °F). Look for the first tiny bubbles, not a simmer. This takes 10–15 minutes depending on volume.Gentle heating coaxes the deep umami compounds into solution. Boiling releases kombu's mucilaginous polysaccharides, clouds the broth, and produces a fishy, bitter, iodine-like off-note.
- 3At the first sign of a true simmer (water at 65–70 °C / 149–158 °F), remove the kombu immediately. Do not let the water reach a rolling boil.The kombu is removed at the edge of a simmer to extract maximum glutamate content without breaching the threshold where slimy polysaccharides dissolve. This is the single most consequential decision in the entire process.
- 4Bring the liquid to a full boil, then remove from heat entirely. Add the freshly shaved katsuobushi all at once. Stir once gently, then let steep for 30–60 seconds without stirring further.Boiling water deactivates the oxidative enzymes in katsuobushi that would degrade its delicate aroma compounds. The steep is brief—katsuobushi gives up its nucleotides (especially inosinate and guanylate) almost immediately. Over-steeping extracts bitter protein fractions.
- 5Strain through a fine-mesh strainer lined with dampened cheesecloth or a paper coffee filter. Do not press the solids. Cool immediately in an ice bath or transfer to a clean container.Pressing compresses the katsuobushi and forces cloudy, bitter particulate into the liquid. Straining gently preserves clarity and clean flavor. Immediate cooling prevents residual heat from continuing extraction and protects the delicate aromatic profile.
Techniques that matter
Temperature-boundary extraction
The entire ichiban dashi method is governed by temperature: kombu is infused cold-to-warm (never boiled), katsuobushi is steep-blanched in fully boiled water then quickly strained. Each ingredient's optimal extraction window is different and separated by method.
Umami synergy (glutamate + inosinate amplification)
Kombu is rich in free L-glutamate; katsuobushi is rich in 5'-inosinate. The glutamate-to-inosinate ratio in this broth creates a synergistic umami amplification—per the umami discoverer Kikunae Ikeda's own work—approximately 1:1 to 5:1 (glutamate to inosinate) yields the peak savory impression.
Enzymatic deactivation by blanching
Fresh katsuobushi contains lipolytic and proteolytic enzymes. A full boil deactivates these instantly, preventing off-flavor development during the brief steep. This is why katsuobushi is added to already-boiled water, not simmered with kombu.
Variations & derivatives
Awase dashiJapan
The standard everyday dashi, identical to ichiban dashi but with a small amount of sake (15–30 mL per liter) and/or mirin added to round the flavor. Used in most household and restaurant kitchens.
Himo-dashiKyoto / Kansai region
Kombu-only dashi; katsuobushi omitted entirely. Intentionally pale and delicate. Used in shojin ryori (temple cuisine) and for delicate preparations like clear soups (suimono).
Niban dashi (second dashi)Japan
A second, lighter extraction using the same kombu from ichiban dashi plus fresh katsuobushi in slightly less water. Produces a cleaner, more mineral, less intensely fishy profile. Used in lighter dishes like hiyayakko or diluted into soups.
Ishikari dashiHokkaido
Dashi made from dried cod (tara no himono) in addition to or instead of katsuobushi, reflecting Hokkaido's fishing heritage. Richer, deeper, more mineral-sweet. Used in ishikari-nabe and regional miso soups.
Used in these dishes
Substitutions
- Katsuobushi → Dashi powder (hon-dashi / granular dashi) — Contains chemically identical nucleotides and glutamates (often from sardine or other fish sources). Use at approximately 5 g per liter instead of katsuobushi. The flavor is noticeably more direct and less complex; the broth lacks the aromatic subtlety of real katsuobushi.changes result
- Kombu → Kombu dashi powder — Reconstituted powder containing kombu extract. Functional for glutamate content but lacks the textural and aromatic complexity of steeping real kombu. Not recommended for clear soups or refined preparations.changes result
- Both kombu and katsuobushi → Vegetable dashi with mushrooms — Kombu can be replaced with dried shiitake for a plant-based dashi (dashi mansi), but this is a different stock entirely—the nucleotide profile changes from inosinate to guanylate, the flavor profile shifts from oceanic to earthy, and the result is not ichiban dashi. Acceptable for vegan preparations but must be labeled as such.changes result
Troubleshooting
Dashi tastes bitter, slightly fishy, or iodine-like
Kombu was boiled, not infused. Temperature exceeded the polysaccharide extraction threshold, releasing astringent compounds. Or katsuobushi was simmered with the liquid instead of steep-blanched. → Restart with fresh ingredients. The critical fix is temperature control: never boil kombu; never add katsuobushi before boiling.
Dashi is cloudy or has a murky appearance
Straining without cloth or paper filtration; pressing the spent katsuobushi; reboiling the strained dashi; using pre-shaved oxidized katsuobushi. → Strain through dampened cheesecloth or a paper filter without pressing. Use only freshly shaved katsuobushi, and cool the finished broth immediately.
Dashi tastes flat or lacks umami depth
Kombu was of poor quality or old; insufficient steeping time in cold water; kombu removed too early (before adequate glutamate extraction); insufficient katsuobushi relative to kombu, breaking the umami synergy ratio. → Use quality fresh kombu (pliable, dark green, aromatic). Ensure 30-minute minimum cold soak. Verify katsuobushi is freshly shaved with a plane or grater immediately before use.
Dashi develops off-flavors or sourness within hours
Cooling too slowly after straining; leaving at room temperature; using contaminated equipment; not cooling below 4 °C fast enough. → Cool in an ice bath to below 4 °C within 30 minutes. Transfer to a clean, sealed container and refrigerate immediately. Use within 2–3 days.