In a large bowl, combine the salt, black pepper, chili powder, cumin, garlic powder, onion powder, smoked paprika, and oregano. Rub the spice mixture all over the beef chunks.

In a slow cooker, add the seasoned beef, beef broth, diced tomatoes, chopped onion, minced garlic, guajillo peppers, and apple cider vinegar. Stir to combine.

Cover and cook on low for 8 hours or on high for 4 hours, until the beef is tender and easily shredded.

Once cooked, remove the beef from the slow cooker and shred it using two forks. Return the shredded beef to the slow cooker and stir to combine with the juices.

To assemble the tacos, heat a skillet over medium heat. Lightly toast each corn tortilla for about 30 seconds on each side.

Fill each tortilla with a generous amount of the shredded beef mixture. Top with chopped cilantro and diced onion. Serve with lime wedges on the side.