Cook stew meat in a large skillet over medium heat for 4 minutes, stirring often. Add onion, garlic, carrots, mushrooms, parsley, salt and pepper and cook for an additional 5 minutes.
Add contents of the skillet to a crockpot along with beef broth, water, barley, tomato paste, Worcestershire sauce and diced tomatoes. Mix well and cook on High heat for 4-5 hours or Low heat for 7-8 hours.