Fermenting mushrooms is a great way to preserve them and add tangy, umami flavours. You can ferment nearly any edible mushroom, but meaty varieties like shiitake, oyster, or button mushrooms work especially well.

Basic Fermented Mushroom Recipe

Ingredients

500g fresh mushrooms (cleaned and sliced if large) 2% salt by weight (i.e. 10g salt per 500g mushrooms) Optional extras: Garlic cloves Spices (e.g. black pepper, chilli flakes) Fresh herbs (e.g. thyme, dill) Bay leaves

Equipment

Clean glass jar with a lid or airlock Weight to keep mushrooms submerged (a small jar or fermentation weight works)

Instructions

Clean the mushrooms with a damp cloth or brush. Avoid washing in water if possible to prevent excess moisture. Slice larger mushrooms into bite-sized pieces. Weigh the mushrooms and calculate 2% salt by weight. Massage the salt into the mushrooms until they start to release liquid (5–10 minutes). Pack mushrooms tightly into the jar, pressing down to submerge them in their own brine. Add spices/herbs between layers if using. Weigh down the mushrooms to keep them submerged. Cover the jar loosely (or use an airlock lid). Ferment at room temperature (18–22°C is ideal) for 5–10 days. Start tasting after 4 days. Longer ferments = tangier flavours. Refrigerate when you’re happy with the flavour. Keeps for several months chilled.

Tips

If there isn’t enough liquid after a day, you can top up with a 2% brine (20g salt per litre of water). A bit of white film on the surface (kahm yeast) is harmless; just skim it off.