Vegetarian Rassolnik (Russian Barley and Pickle Soup)

Ingredients

• 1/3 cup pearl barley
• 6 cups water
• 2 tablespoons butter
• 1 medium onion, minced
• 1 (12 ounce) package button mushrooms, chopped
• 2 medium potatoes, diced
• 1 carrot, diced
• 2 large bay leaves
• 1 tablespoon dried dill
• salt and freshly ground black pepper to taste
• 3 pickles, diced
• 1/4 cup sour cream, for topping