Soak dried mushrooms in hot water to cover for 30 minutes. Strain through a filter, reserving the water. Coarsely chop the soaked mushrooms.
Melt the margarine in a stockpot and saute the onion, celery, 2 tbsp of parsley, carrot, garlic, soaked mushrooms, and fresh mushrooms until soft (about 5 minutes).
Lower the heat and add the flour, stirring every 30 seconds or so for about 5 minutes until thick.
In a soup pot, heat the broth/water. Add a cup of the mushroom mixture at a time to the pot, stirring.
Turn the heat to high. Add the reserved mushroom water and barley. Stir well and salt to taste. Simmer, covered, for about an hour or until the barley is tender and the soup is thickened, stirring often.
Add additional chopped parsley. Mix thoroughly and adjust seasonings.