Creating Pulled Beef Tacos is a straightforward process when you follow these steps:

1. Sear the Beef: In a large skillet, heat olive oil over medium-high heat. Sear the beef chuck on all sides until browned, about 3-4 minutes per side. Transfer to a slow cooker.

2. Sauté Onions and Garlic: In the same skillet, add chopped onions and minced garlic. Sauté for about 2-3 minutes until softened and fragrant.

3. Mix Spices: In a small bowl, combine chili powder, cumin, smoked paprika, salt, and black pepper. Add this spice blend to the sautéed onions and garlic, stirring for an additional 1-2 minutes.

4. Combine Ingredients: Pour the beef broth, apple cider vinegar, and brown sugar into the slow cooker. Add the sautéed mixture on top of the beef.

5. Cook the Beef: Cover the slow cooker and cook on low for 4-6 hours, or until the beef is fork-tender. If using an Instant Pot, set it on high pressure for 60 minutes, then allow for a natural release.

6. Shred the Beef: Once the beef is cooked, remove it from the slow cooker and shred it with two forks. Return the shredded beef to the sauce, mixing well.

7. Warm the Tortillas: Heat the tortillas in a dry skillet over medium heat for about 30 seconds per side or until warm and pliable.

8. Assemble the Tacos: Place a generous amount of shredded beef onto each tortilla. Top with cilantro, diced tomatoes, and avocado.

9. Serve with Lime: Serve tacos with lime wedges on the side for squeezing over the top.

10. Enjoy: Gather everyone around the table and enjoy these incredible Pulled Beef Tacos!