Trim any large pieces of excess fat from the chuck roast and season all sides evenly with the sea salt and black pepper.
Place the seasoned beef into the bottom of your slow cooker.
Prepare the vegetables by peeling and chopping the carrots and parsnips into 1-inch rounds, and dicing the yellow onion.
Arrange the carrots, parsnips, and onion around the beef in the slow cooker.
In a small mixing bowl, whisk together the beef bone broth, tomato paste, minced garlic, dried thyme, and dried rosemary until well combined.
Pour the broth mixture over the beef and vegetables.
Cover the slow cooker and cook on low heat for 8 hours (or high for 4-5 hours) until the beef is fork-tender and pulls apart easily.
Remove the beef from the slow cooker and shred it slightly with two forks before serving alongside the softened root vegetables and a ladle of the savory cooking liquid.