Step 1: Sear the Beef (Optional but Recommended): Heat a large skillet over medium-high heat. Sear the chuck roast on all sides until browned, about 2-3 minutes per side. This step adds depth of flavor to the beef. If you prefer, you can skip this step and go directly to placing the beef in the slow cooker or Dutch oven.
Step 2: Prepare the Slow Cooker (or Dutch Oven): In a slow cooker (6-quart or larger), or a Dutch oven, place the chopped onion, minced garlic, diced tomatoes (undrained), and diced green chilies. If using a Dutch oven, ensure it is oven-safe.
Step 3: Season the Beef: In a small bowl, combine the chili powder, cumin, smoked paprika, oregano, cayenne pepper (if using), salt, and black pepper. Rub the spice mixture generously over the seared chuck roast, ensuring it is evenly coated.
Step 4: Slow Cook (or Bake): Place the seasoned chuck roast on top of the vegetables in the slow cooker. Pour the beef broth and apple cider vinegar over the beef. Cover the slow cooker and cook on low for 6-8 hours, or on high for 3-4 hours, until the beef is very tender and easily shreds with a fork. If using a Dutch oven, cover and bake in a preheated oven at 325F (160C) for 3-4 hours, or until the beef is very tender.
Step 5: Shred the Beef: Remove the chuck roast from the slow cooker or Dutch oven and place it on a cutting board. Use two forks to shred the beef into bite-sized pieces. Discard any large pieces of fat.
Step 6: Return to Sauce: Return the shredded beef to the slow cooker or Dutch oven, mixing it with the cooking juices. This allows the beef to absorb even more flavor.
Step 7: Warm the Tortillas: While the beef is simmering, warm the tortillas according to package instructions. You can warm them in a dry skillet, in the microwave, or in the oven.
Step 8: Assemble the Tacos: Fill each warmed tortilla with the shredded beef. Top with your favorite toppings, such as shredded cheese, salsa, sour cream, guacamole, cilantro, diced onions, and a squeeze of lime juice.
Step 9: Serve and Enjoy: Serve the pulled beef tacos immediately and enjoy!
Optional Tips:For a richer flavor, use a dark beer instead of beef broth. For a spicier kick, add a chopped jalapeo to the slow cooker. The shredded beef can be made ahead of time and stored in the refrigerator for up to 3 days, or frozen for up to 2 months.