To make mushroom powder, you need to combine all of the above ingredients in the quantities mentioned and blend/ grind it in a food processor or blender. Continue blending it till it turns into a fine powder.
Once done, you can store it in an airtight container, which you can then keep in a cool place for days together. Use a fine-mesh strainer to pour the powder into the glass container. Add a pinch of the powder to soups, salads, pasta, and the like to get the delicious umami flavor.
Note that this powder is fine, which is why you need to be extra careful while removing the lid of the blender to empty it into an airtight container. Failing to do so can result in a complete mess, which will make it a cumbersome task to clean.