Combine all spices in a small bowl.
Pat the chuck roast dry and rub the seasoning mixture over the meat.
Sear the beef on all sides in a skillet with cooking oil until golden brown.
Place the seared beef in the slow cooker with diced onions and minced garlic.
Pour in beef broth and stir in tomato paste.
Cover and cook on low for 6 to 8 hours or on high for 3 to 4 hours.
Transfer the roast to a cutting board and shred it with two forks.
Return the shredded beef to the slow cooker and mix with the sauce. Squeeze lime juice on top.
Serve the warm shredded beef in tacos, burritos, or bowls with your favorite toppings.
