Rinse the beef chuck roast under cold water and pat dry. Cut off any large pieces of fat.
Heat olive oil in a large skillet over medium-high heat. Season the beef with salt and black pepper, then sear for 4-5 minutes on each side.
Remove the beef and sauté chopped onion for 3-4 minutes, then add minced garlic and cook for 1 minute.
Return the beef to the skillet, add beef broth and diced tomatoes, bring to a simmer, cover, and cook on low for 3-4 hours.
Shred the beef with two forks and return to the skillet. Stir in lime juice and simmer for an additional 10 minutes.
Warm corn tortillas and assemble tacos with shredded beef and fresh cilantro. Serve with lime wedges.