01 - Distribute sliced onion and minced garlic evenly across the bottom of the slow cooker insert.
02 - Whisk together beef broth, tomato paste, and Worcestershire sauce in a small bowl until smooth and fully incorporated.
03 - Combine chili powder, cumin, smoked paprika, oregano, salt, black pepper, and cayenne in a small bowl. Massage spice mixture thoroughly over all surfaces of the chuck roast.
04 - Place seasoned roast directly on top of onion and garlic bed in slow cooker.
05 - Pour broth mixture evenly over the seasoned beef.
06 - Cover and cook on low setting for 8 hours until beef easily shreds with a fork.
07 - Transfer cooked roast to cutting board. Using two forks, pull meat apart into shreds. Return shredded beef to slow cooker and toss thoroughly with accumulated juices.
08 - Serve hot in tacos, sandwiches, rice bowls, or as desired.