Kombu

On its own, dried kombu kelp has a mild, faintly briny flavour. Its real contribution is what it does to the liquid around it: it draws out savoury depth without adding a strong ‘seaweed’ taste. Dashi made from kombu tastes clean, savoury and subtly sweet, depending on the variety used.

Place roughly 10g of kombu per litre of cold water in a pot or container. For a cold soak, leave it in the fridge for 30 minutes to overnight. For a heat method, warm the water slowly and remove the kombu just before it boils. Either method produces a clear, umami-rich stock. For a stronger dashi, add katsuobushi (bonito flakes) or dried shiitake after removing the kombu.

Cold soaking gives a cleaner, more delicate dashi and is very forgiving. The heat method is faster, but you need to warm slowly and remove the kombu before the water boils to avoid bitterness or a slimy texture.

A good starting point is about 10g per litre. If you want a lighter stock, use a smaller piece. If you want it stronger, increase the kombu slightly or steep for longer rather than boiling.

Yes. Once you’ve lifted the kombu out, it still has flavour and texture. Slice it into thin strips and simmer with soy sauce and mirin for an easy tsukudani-style condiment or add it to simmered dishes.

Absolutely. Kombu alone makes a light, savoury stock. For a deeper plant-based version, steep kombu with dried shiitake. The two work well together and give a fuller broth without using fish.

Yes. Add a small strip to the pot as the rice cooks, then remove it before serving. It won’t make the rice taste “seaweedy”. It simply adds a gentle savoury note that makes the rice taste fuller.

The closest kombu substitute for dashi is kombu dashi powder, which dissolves in hot water. For umami from other sources, dried shiitake mushrooms, miso paste or soy sauce can partially fill the gap. Other seaweeds like wakame or nori won’t replicate kombu’s glutamate levels or its effect in stock.

It’s better kept in a cool, dry cupboard in an airtight container. Fridges add moisture, which shortens shelf life. If you see a white bloom during storage, that’s usually mannitol and it’s normal.

Stored in an airtight container in a cool, dry cupboard, dried kombu keeps for months or even years. It can improve with age, becoming more concentrated in flavour. Avoid storing it in the fridge, as moisture will reduce its shelf life.