Trim any excess visible fat from the beef chuck roast and season all sides evenly with sea salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat and sear the beef for 3-4 minutes per side until a deep brown crust forms.
Prepare the vegetables by halving the baby potatoes, slicing the carrots into thick rounds, and chopping the yellow onion into large chunks.
Place the potatoes, carrots, and onions in the bottom of the slow cooker, then rest the seared beef on top of the vegetables.
In a small bowl, whisk together the beef broth, tomato paste, minced garlic, and dried thyme until well combined.
Pour the broth mixture over the beef and vegetables, ensuring the liquid covers at least half of the roast.
Cover and cook on the low setting for 8 hours until the beef is tender and easily shreds with a fork.
Remove the beef to a cutting board to rest for 5 minutes before slicing or shredding, then serve alongside the tender vegetables and a ladle of the cooking juices.