The Best Way to Rinse Mushrooms
Some people will say that mushrooms should not be washed because they absorb water and are difficult to cook. But it’s doable if you have a salad meter and a few extra seconds to spare.
As Serious Eats’ J. Kenji Lopez-Alt explains, you don’t need to spend a lot of time wiping mushrooms with a paper towel or need a special mushroom brush. If you do it right, they can be rinsed out. Wash the mushrooms in cold running water, then toss them into the salad bowl. Scroll through them until they are as dry as possible, then cook and cook them as usual. Add a few extra seconds of cooking time to compensate for the slight excess moisture and you’re done. But do this only just before cooking, as moisture will drastically shorten the shelf life of the mushrooms.
Knife skills: how to cook mushrooms (and whether to wash them) | Serious food