Heat the olive oil in a large skillet over medium-high heat. Add the beef cubes and brown them on all sides for about 5 minutes.
Sprinkle the flour over the beef and stir to coat evenly. Cook for 1 minute more.
Transfer the beef to the slow cooker. Add the carrots, potatoes, parsnip, onion, and garlic.
In a bowl, whisk together the beef broth, tomato paste, thyme, salt, and pepper. Pour this mixture over the meat and vegetables in the slow cooker.
Add the bay leaves, then cover and cook on low for 8 hours.
Remove the bay leaves before serving.