How do you know if a mushroom is cooked?

1. Keep the mushroom dry. Slightly damp paper towel to brush off any dirt on the mushrooms. In any case your mushrooms are extremely dirty, dunk them quickly into water, and make sure you pat them extra dry before cooking them. Do not rinse or submerse them in water. Water will be absorbed as mushrooms act like a sponge, which makes the cooked mushrooms to be squeaky instead of flavorful and browned.
2. Slice or tear the mushrooms into same size. For a variety of mushrooms, slice the mushrooms into same size. If they are more fragile, tear the mushrooms.
3. Do not put too much mushrooms in the pan. They will steam if you stack raw mushrooms on top of each other in a pan. They will brown and crisp around the edges if you spread them out in one layer and they are only just touching one another. Use a wide heavy pan or cast iron.
4. Season mushrooms with salt towards the end of cooking. Salt brings out moisture, which prevents the mushroom from browning in the pan. Brown the mushrooms before adding the salt and seasonings.

For your convenience, try shiitake mushroom jerky from Vegky[1]. These are cooked, packaged, and ready to eat.

**As seen in: https://www.quora.com/How-do-you-know-if-a-mushroom-is-cooked