Brown the beef in a skillet over medium heat.
Transfer the browned beef to the slow cooker.
Sauté the onions and garlic in the same skillet.
Add sautéed onions and garlic to the slow cooker.
Stir in the mushrooms, beef broth, Worcestershire sauce, paprika, salt, and pepper.
Cover and cook on low for 8 hours or high for 4 hours.
Stir in the sour cream before serving.
Serve hot, garnished with fresh parsley.