Mushroom Barley Soup

• 2 potato (peeled)
• 2 carrots (whole peeled)
• 1 onion (minced)
• 1 bay leaf (whole)
• 1/4 barley fine
• 1,400 ml chicken broth
• 350 ml water (hot)
• 28 gr mushrooms (dried)
• 28 gr butter