Soak the mushroom in hot water for 20 minutes. Meanwhile peel the root vegetables and chop them into bite-sized cubes. Slice the carrots and the leek.
Drain the mushrooms, but retain the soaking water, and chop them roughly.
Heat the oil in a large saucepan and sauté the chopped vegetables for 2-3 minutes. Add the barley, mushrooms and the bay leaf. Pour in the soaking-water of the mushrooms and vegetable stock. Season to taste with salt and pepper.
Bring the broth to the boil, them simmer at a low temperature, under cover, for 1 hour.
Before serving, sprinkle some parsley on top.