Heat olive oil in a large skillet over medium-high heat.
Add beef chunks to the skillet and brown on all sides, about 3-4 minutes per side.
Transfer browned beef to the crock pot.
Add sliced onion and minced garlic on top of the beef in the crock pot.
In a medium bowl, whisk together beef broth, Worcestershire sauce, soy sauce, brown sugar, dried thyme, smoked paprika, black pepper, and salt.
Pour the sauce mixture over the beef and onions in the crock pot.
Cover and cook on low for 8 hours or until the beef is very tender and easily shredded.
Remove beef from the crock pot and shred it using two forks.
Return shredded beef to the crock pot and stir to combine with the juices.
To serve, pile the shredded beef onto the sandwich buns and spoon some of the cooking juices over the top.