Place the beef cubes, carrots, parsnips, potatoes, and onion into the slow cooker.
In a bowl, whisk together the beef broth, tomato paste, thyme, salt, and pepper until smooth.
Pour the broth mixture over the beef and vegetables in the slow cooker.
Cover and cook on low for 8 hours until the beef is fork-tender.
Ladle the stew into bowls and serve with slices of crusty bread on the side.