Clean the mushrooms - to do this, DON'T use water. Instead, lightly clean them with a kitchen towel or using a gentle brush. If there's some stubborn dirt, then use a damp kitchen towel.
Depending on what variety you're using, you can choose to dry them whole or sliced (around 1/8"/1cm in thickness). Most mushrooms will need to be sliced.
Arrange the mushrooms onto the dehydrator tray/s (for the dehydrator) or parchment-lined baking tray/s (for the oven) in a single layer, with a little space between - for the air to circulate. Make sure to blot the mushrooms with a paper towel before they go in the oven/dehydrator, to remove any other excess water (and avoid them steaming in the oven!).
In The Oven
Dry the mushrooms in the oven at around 130ºF/54ºC for 4-8 hours, flipping them over after 1-2 hours (and repeating this process every 1-2 hours), and blotting with a paper towel to remove excess liquid. If your oven doesn't go below around 140ºF/60ºC, then it's a good idea to prop open the door with a heat-proof wooden spoon or potholder. Not only will this bring down the temperature of the oven, but it will also increase air-flow. If the temperature is too high the mushrooms can 'case harden' - which means the outer layer will become hard ('cooked') and make it harder for the remaining moisture to escape.
Remove the dehydrated mushrooms from the oven and allow them to cool completely. They will continue to crisp up as they cool.If they aren't completely dry (they should snap rather than bend and be fairly brittle), you can place them back in the oven for longer.
With A Dehydrator
Dehydrate the mushrooms, in a single layer, at 125ºF/52ºC until the mushrooms are leathery and dry.This process can take anywhere from 4-12 hours depending on the thickness of the mushrooms, how big your batch is in the machine, and even the humidity. It's worth checking on them every hour.
How To Make Mushroom Powder
Place the dried mushrooms in a high-speed blender/food processor and blend into a fine powder. You may want to sieve the powder and re-blend any larger bits or separate them into different containers.
To make a quick mushroom seasoning: add some salt to the mushrooms when blending. It can also be great to use a combination of dried mushrooms for different flavors.Optional add-ins: garlic powder, red pepper flakes, or chili powder
How To Store
Store the dried mushrooms in an airtight container (I use glass jars) in a cool, dark place away from direct sunlight for up to 12 months.The mushroom powder will remain at its peak flavor for 6 months but will be fine for up to 12 months.Top Tip: in the immediate days after drying the mushrooms, check for moisture in the container (condensation, etc.). If there is, then repeat the drying process for a little longer. Otherwise, the entire batch of dried mushrooms will become moldy.
Make sure to only use mushrooms that are fresh (not past their best) and with no black spots or mold.
If you forage for mushrooms be careful about selecting only species that are edible and non-toxic. Some edible species include Agaricus (common/button), Boletus (Cep/Porcini), etc. It's best to use a chart or there are even mushroom identification apps you can use on your phone.
Check the main blog post content for tons of ways to use the resulting dried mushrooms and mushroom powder, as well as how some top FAQs