Clean mushrooms with a dry brush or damp cloth
Trim off any damaged or tough parts
Slice mushrooms evenly
Arrange in a single layer on dehydrator trays or baking sheets
Dry in a dehydrator at 125°F to 135°F until crisp
Or dry in an oven at its lowest setting with the door slightly open
Check and rotate trays if needed for even drying
Continue drying until mushrooms are completely brittle
Let mushrooms cool to room temperature
Store in an airtight container in a cool, dark, dry place
Rehydrate in warm water or broth before using