How to Make Dashi: The Complete Guide to Japanese Stock

Dashi is a Japanese cooking stock made by briefly steeping or simmering dried ingredients in water to extract their glutamates and nucleotides — the chemical compounds responsible for umami flavour. The most common dashi is awase dashi, made from kombu (dried kelp, rich in glutamates) combined with katsuobushi (dried, fermented, smoked skipjack tuna flakes, rich in inosinate). When glutamates and inosinate combine, their umami effect is synergistic — the resulting flavour is far more than the sum of its parts. This is why dashi tastes so much more complex than either ingredient alone. Dashi is used at a ratio that would shock Western cooks: it is often 90–95% of the liquid in a soup or sauce, not a background note but the primary flavour vehicle.

Ichiban dashi (一番だし) is the first extraction — the clearest, most delicate and most flavourful dashi. It is used where the dashi's flavour is the centrepiece: clear soups (suimono), chawanmushi (steamed egg custard), and sauces for cold noodles. Method: wipe a 10 g piece of kombu with a damp cloth (do not wash — the white powder is dried umami compounds). Place in 1 litre cold water and heat slowly over medium-low heat. Remove the kombu just before the water boils (at around 60–65°C), when small bubbles begin rising from the kombu. Add 20–25 g of loosely packed katsuobushi. Bring to the edge of boiling, then immediately remove from heat. Let the katsuobushi steep for 3–4 minutes. Strain through a fine sieve lined with a damp cloth. Do not squeeze the katsuobushi — it makes the dashi bitter.

Niban dashi (二番だし) uses the kombu and katsuobushi that were strained from ichiban dashi. It produces a slightly more robust, earthier stock that is ideal for miso soup, simmered dishes (nimono), and dishes where the dashi is one flavour layer among many rather than the solo voice. Method: return the strained kombu and katsuobushi to the pot. Add 1 litre fresh water. Bring to a gentle simmer and cook for 10–15 minutes. Add a small handful of fresh katsuobushi and steep for 2 minutes off the heat. Strain. Niban dashi is slightly cloudier but equally valuable — professional Japanese kitchens use both, wasting nothing.

Kombu dashi uses only dried kelp and produces a clean, mineral, gently umami stock that is entirely plant-based. It is the preferred base for vegetable dishes, tofu preparations and vegan Japanese cooking. Cold method (best for clarity): place 10 g kombu in 1 litre cold water and refrigerate for 4–12 hours. Strain and use. Gentle heat method: heat kombu in cold water over very low heat to 60°C, steep for 15 minutes, remove kombu, strain. The cold method produces the most delicate, clear dashi; the heat method is faster and slightly more concentrated.

Dried shiitake mushrooms are extraordinarily rich in guanylate — a nucleotide that, like inosinate in bonito, synergises powerfully with kombu glutamates. Shiitake dashi is made by cold-steeping 20–30 g dried shiitake mushrooms in 1 litre cold water in the fridge overnight. The resulting stock is deep mahogany in colour, intensely savoury and almost fungal in the best possible sense. It is the most flavourful vegan dashi and is used in ramen vegetable broths, vegan miso soup, noodle sauces and simmered vegetables. The rehydrated shiitakes are valuable in their own right — use them sliced in stir-fries, as a topping for rice bowls or as a filling for gyoza.

Instant dashi powder (dashi no moto) is a legitimate shortcut for everyday weeknight cooking. The best brands (Ajinomoto Hondashi, Kayanoya) produce a stock that is flavourful and convenient. Use instant dashi for miso soup and nimono on busy weeknights; make ichiban dashi from scratch for dishes where dashi is the feature. Quantity: typically 1 teaspoon of powder per 2 cups (500 ml) of water. Instant kombu dashi powder also exists for vegan cooking. Avoid cheap brands that rely entirely on MSG without natural kombu or bonito flavour — the result is flat and one-dimensional.