Prepare the Beef: Season the chuck roast with salt and pepper. Heat olive oil in a large pot over medium heat, then sear the roast on all sides until browned, about 8-10 minutes.
Cook the Aromatics: Remove the roast and set it aside. Add diced onion and garlic to the pot, cooking until softened.
Braise the Beef: Return the roast to the pot and add beef broth, chili powder, cumin, smoked paprika, oregano, and a bay leaf. Bring to a simmer, then reduce the heat, cover, and braise for 3 hours or until the roast is tender and shreddable.
Shred the Beef: Remove the chuck roast, discard the bay leaf, and shred the beef using two forks. Return the shredded beef to the pot to soak in the braising liquid.
Assemble the Tacos: Warm the tortillas and fill each with the braised beef. Top with cilantro, pickled onions, and a squeeze of lime.
Serve and Enjoy! Add hot sauce if desired for an extra kick.