Trim the mushrooms and halve or quarter them, depending on size.
Peel and finely chop the onions and garlic. Sauté the onions in some oil until soft and then add the garlic. Stir in the mushrooms and fry until the mushroom juice is almost evaporated.
Season with salt and pepper and shower with the chopped parsley.
Transfer the mushrooms to a preheated plate and serve immediately with fresh bread if desired.