In a decent size skillet, add some vegetable oil and fry those mushrooms along with the garlic until you are satisfied with the result. I usually like them well cooked.
In a large pot melt butter over medium heat then add celery, carrots and onion, cook and stir for 5 minutes. Add mushrooms and garlic; cook and stir for another 5 minutes.
Stir in broth and 2 cups of water, tomato paste, salt and pepper to taste; bring to boiling. Stir in your barley and reduce heat to low; cover and simmer for 30 minutes or until barley is tender.
Add parsley and serve hot.
Recipe by CookingGlory at http://www.cookingglory.com/recipes/meal-ideas/soups-stews/mushrooms-and-barley-soup/