I’ve had so many arguments with people about dirt on mushrooms over the years, both when I worked in restaurants and when I simply cooked for others or ate what someone else served. It’s one of those “Slowly I turned” things for me now and I tend to go off on people who tell me you never wash the mushrooms. Grrr. So many people say that and think they are gourmets and then serve you mushrooms with the dirt still on them. People who worked with me in restaurants did that, because it made them sound knowledgeable and it was easier than washing the mushrooms. Kitchen people I worked with even told me that customers liked the mushrooms that way, it gives them an earthy flavor.
So, whatever you want to believe is fine, but I will remove the dirt somehow even if I must wash the shrooms. If you serve me stuffed mushrooms with that gourmet trace of dirt on the platter underneath, and that cosmetically wonderful feeling of grit when I bite into them, I’ll send them back. Earthy flavor, my hinder. Lazy cook.
It’s true that you can often harvest wild mushrooms and prepare them without washing them at all. In the forest, mushrooms are pretty clean and I’ve picked lots of them that needed no prep. Sometimes there is debris on the cap or on the stem and the brush at the end of a mushroom knife is there to gently brush it off the mushroom. You are not supposed to save the dirt because it adds to the flavor. I actually see no point in the blade, so a little paintbrush would do just as well, but mushroom knives are handy in other ways too, and I wouldn’t go into the woods without a knife of some sort. There are all kinds of reasons to need one.
If mushrooms are really dirty, you do need to wash them. Button mushrooms, the type that hasn’t opened far enough to expose gills, aren’t harmed at all by washing. Gilled mushrooms already open, well, if you flush the bottom of the mushroom, you wash away some spores and reduce flavor, in theory. You can wash dirt off the cap without affecting flavor, and you should. In actuality, I doubt anyone can tell the difference in flavor, but people do detect dirt and grit. Commercially grown Agaricus mushrooms found in groceries, either white or brown, should be washed whether caps are open or closed. The medium these mushrooms occupy when growing is rich in manure. Even if it’s composted and sterilized, as it usually is, I don’t want to eat that.
If a wild mushroom is clean after that first brushing, just cook it. If it isn’t, then you should wash it. Sometimes you may find mushrooms already being eaten by something else, and if they are in good shape you can save them by soaking them in brine for a few hours. Insect larvae mostly exit the mushroom during the soak, and any of them that are left taste like mushroom. Kind of like my Uncle Lewis’s cherry pie, he never bothered to pull out the worms in the cherries because as he said, they were just full of cherry. The same thought can be applied to mushrooms.
My most recent confrontation over this issue of washing or not washing mushrooms was with my sister, who is one of those fancy people who follows gourmet rules. I noticed her slicing mushrooms directly from box to food and I said, “Are you washing those?”
She said, “You never wash mushrooms!”
I gave her my Mushroom speech and told her why that is a fallacy. She brushed the dirt off reluctantly and I could see she was angry. I calmed myself and ate the meal. I suppose she missed that earthy flavor, but I prefer the mushrooms to the dirt.