Season the beef chuck roast with salt and black pepper on all sides.
Heat olive oil in a large skillet over medium-high heat. Sear the beef roast for about 4-5 minutes per side until it develops a nice brown crust. Remove from heat and set aside.
In the slow cooker, add the diced onion, minced garlic, ground cumin, dried oregano, smoked paprika, minced chipotle peppers, apple cider vinegar, and beef broth.
Place the seared beef roast on top of the onion and spice mixture. Squeeze the lime juice over the beef.
Cover the slow cooker and cook on low for 8 hours, or until the beef is fork-tender.
Once cooked, remove the beef from the slow cooker and shred it using two forks.
Return the shredded beef to the slow cooker and mix it with the sauce, allowing it to soak up the flavors for an additional 15 minutes.
Serve the shredded beef in corn tortillas, garnished with fresh cilantro if desired.