Trim excess fat from the chuck roast and place it in the slow cooker (or Dutch oven if cooking on the stovetop).
Make the sauce
In a bowl, whisk together the beef broth, BBQ sauce, apple cider vinegar, Worcestershire sauce, and all the seasonings.
Cook the beef
Pour the sauce over the beef, ensuring it’s well-coated. Cover and cook on low for 6 hours (or 325°F for 3 hours in a Dutch oven).
Shred the meat
Once the beef is fork-tender, remove it from the slow cooker and shred it using two forks. Return the shredded beef to the sauce and stir to coat.
Warm the tortillas
Heat them on a dry skillet for about 30 seconds per side or until lightly charred.
Assemble the tacos
Fill each tortilla with a generous amount of shredded BBQ beef. Top with red onion, cilantro, and jalapeño slices if using. Serve with lime wedges for squeezing over the top.