I recently stayed with a friend living in Epernay, in France's Champagne region. As she and her husband like to eat and I love to cook, we stayed in for all our meals. Before I arrived, they stocked their fridge with artichokes, tomatoes, tiny, sweet plums and a kilo each of chanterelles and cepes. That's a lot of mushrooms.
I started cleaning them the way I was taught - by gently brushing off the soil. My friend didn't have a mushroom brush, though, so I had to use a pastry brush that was too soft. It would have taken hours to clean them this way so I filled the sink with water, dumped in a few handfuls of mushrooms and gave them a quick rinse. It almost felt as if I were committing a culinary faux pas because I've heard over and over again that mushrooms absorb water like a sponge.
Therefore I was happy to see Harold McGee addressing the subject of cleaning mushrooms in his book The Curious Cook. The food scientist weighed some mushrooms, let them soak in water for a few minutes, blotted them, then weighed them again. The amount of water they absorbed was minuscule. He writes that mushrooms are made up mostly of water anyway, so what does it matter if they absorb a tiny bit more? According to McGee, the rin- sing should be done just before the mushrooms are cooked.
If you've cooked mushrooms, you will know how much water they contain. Put them in a pan with a little butter or oil, turn up the heat and it won't be long before they're simmering in their own liquid. If they continue to cook, they'll re-absorb the liquid, sucking back in all the flavour. So the trick with cooking mushrooms is either to do it very fast- so they don't have time to release the liquid- or give them enough time.
I use a high heat and a large pan so they're not crowded. If too many mushrooms occupy a small space, it will take longer for the liquid to cook off. A well-seasoned wok is ideal because there's so much surface area.
Roasting them in a hot oven also works well, because although the mushrooms shrivel, the flavour is more intense. Or dip them in a light batter and deep-fry them- the batter forms a protective barrier which locks in the mushrooms' moisture and flavour.