Some time ago, I dined at Celestial Court Chinese Restaurant at Sheraton Hong Kong Hotel & Towers, Kowloon, Hong Kong. I loved their mushroom soup (冬菇湯). I asked their chef for advice, and he said I must soak Chinese dried mushrooms in water for flavour.
What's the science behind this?
I'm supposed to use the left-over standing water as the soup base, correct? Or is it dirty and I ought discard it?
What if I use fresh mushrooms? If I soak them in water, will they result the same as if I used Chinese dried mushrooms?