First imagine a plump, round, fat, juicy mushroom, then think of a shrivelled dried mushroom.
The difference is moisture, and because the dried one has masses more flavour, having lost the moisture, I feel that the thing to aim for when cooking mushrooms is to get as much of the moisture out as possible so as to concentrate the flavour. No need to use very much oil or butter, as mushrooms tend to soak this up at an alarming rate. Always remember, too, that as the moisture evaporates they lose half their original volume.
This recipe is from Delia's Complete How to Cook. Serves 2
Heat the olive oil or butter in a frying pan and, when it’s hot, throw in the mushrooms and toss them around by shaking the pan.
Season with salt and pepper, then turn the heat down to very low and just let the mushrooms cook gently, uncovered, so that all the juice evaporates and the flavour of the mushrooms becomes more concentrated. Leave them like that for 30 minutes, stirring them around once or twice. Once the mushrooms have lost much of their moisture content they can then be used in an omelette or simply as they are.
You could also add a peeled and chopped clove of garlic 5 minutes before the end and finish off with a sprinkling of chopped fresh flat-leaf parsley.