Add the beef stew meat, sliced onion, mushrooms, and minced garlic to the slow cooker.
In a small bowl, whisk together the beef broth, Worcestershire sauce, paprika, salt, pepper, and flour until smooth. Pour this mixture over the beef and vegetables.
Cover and cook on low for 7 to 8 hours until the beef is fork-tender.
About 20 minutes before serving, cook the egg noodles in a pot of boiling water according to package directions, then drain.
Stir the sour cream into the slow cooker until the sauce is creamy and well combined.
Spoon the beef and sauce over the cooked egg noodles and sprinkle with chopped parsley before serving.