Premium Kombu Seaweed Japanese Umami

Kombu is the seaweed behind dashi, the stock that Japanese cooking is built on. Its broad, dark leaves are high in glutamates, which is why a short soak in cold water produces so much flavour.

For dashi, wipe the leaf with a damp cloth rather than washing it — the white powder on the surface is where much of the umami sits. Soak in cold water for a couple of hours, then warm gently and lift the leaf out before the water boils.

Beyond stock, slice it thinly for a vinegar dressing, simmer it with soy and mirin, or drop a piece into a pot of beans for depth. Keep it dry and sealed; it will absorb moisture from the air.

• Thick, broad leaves with a deep green colour
• The base of dashi — soak, do not boil
• Rich in glutamates, the source of umami
• Also good sliced into salads and simmered dishes