Add the onion, carrots, and garlic to your slow cooker. Pour in the broth and then add the beef. Sprinkle beef with sea salt and pepper then rub with Worcestershire sauce and paprika.
Add fresh thyme around the roast.
Cover and cook on low heat for 12-14 hours, until the meat is very tender. (I have cooked this up to 16 hours with good results!) Serve immediately, or store in the fridge for up to 4-5 days as food prep.