Place the beef stew meat in the bottom of the slow cooker.
Add the carrots, potatoes, parsnips, and onion on top of the beef.
In a small bowl, stir together the beef broth and tomato paste until smooth, then pour the mixture over the vegetables and beef.
Sprinkle the dried thyme, salt, and black pepper over the top, then tuck in the bay leaves.
Cover and cook on low for 8 hours until the beef is tender and the vegetables are soft.
Remove the bay leaves before serving.