1. Melt 2 tablespoons butter in a large pot over medium heat. Add grated carrot and chopped onion, saute 2 minutes.
2. Add mushrooms and saute 5 minutes.
3. Add barley and cook for another 2 minutes.
4. Next, add water and chicken broth. Bring to a boil, reduce to simmer and cook for 15 minutes.
5. Add chopped potatoes and continue cooking for another 20 minutes. Season with salt and pepper.
6. Remove from heat and let stand for 5 minutes.
7. Garnish with parsley before serving (optional). Serve with sour cream.