Prepare the beef: Trim any excess fat from the beef roast. Season all sides with salt, pepper, chili powder, cumin, smoked paprika, and oregano.
Layer the Crockpot: Place sliced onions and garlic at the bottom of your slow cooker. Lay the beef roast on top.
Add liquid: Pour beef broth, tomato sauce, and lime juice over the roast.
Cook low and slow: Cover and cook on LOW for 8–10 hours or HIGH for 4–5 hours, until the beef is fork-tender.
Shred the beef: Remove the roast, shred with two forks, then return to the Crockpot to soak up all the flavorful juices.
Assemble tacos: Spoon the pulled beef into tortillas and top with your favorite taco fixings.