Shiitake dashi.

Shiitake has the highest trim loss of anything we grow — 15 to 20% — because the stems are too woody to eat whole. They are also the most flavourful part of the mushroom, which makes throwing them away the single most common waste in a kitchen using shiitake.

This is the fix. A freezer bag of stems, a piece of kombu, cold water and patience. No cooking involved.

What you need

Dashi

• 1 oz dried shiitake, or 4 oz fresh shiitake stems and trim
• 1 piece kombu, about 4 inches
• 1 quart cold water

Optional additions

• Spring onion tops
• A slice of ginger
• A splash of soy or mirin, at the end

Method

1. Combine everything cold. Shiitake, kombu and water in a jar or container. That is the entire active step.
2. Refrigerate 8–12 hours, or overnight. Cold extraction gives a cleaner, sweeter, less bitter dashi than boiling — this is what good ramen shops do.
3. Strain, pressing gently on the solids. Do not squeeze hard or you push bitterness through.
4. If you want it stronger, warm the strained liquid to 150°F and hold it there for 15 minutes. Never boil kombu — it turns slimy and bitter.
5. Season at the point of use, not now. Unseasoned dashi is a base; salt it for the dish it is going into.

Cold, not hot

Boiling shiitake extracts flavour fast and also extracts bitterness and a muddy quality. Cold steeping takes twelve unattended hours and gives a noticeably cleaner, sweeter, more complex liquid. The only cost is planning.

Dried shiitake makes a stronger dashi than fresh. Drying concentrates guanylate, which is the compound doing most of the umami work — see drying mushrooms at home.

What to do with it

• Miso soup — the proper base, instead of water. Recipe here.
• Ramen and noodle broth, alone or blended with chicken stock.
• Braising liquid for greens, tofu or root vegetables.
• Risotto, in place of chicken stock. It is better.
• Tempura dipping sauce, with soy and mirin.
• Frozen in ice-cube trays as umami cubes for anything that needs depth.

The spent solids

The rehydrated stems are still too woody to eat, but they can go through a second, weaker extraction. After that, compost. The kombu can be sliced thin and simmered with soy and mirin into a small side dish.

Common questions