Heat a pan with a tablespoon olive oil on medium high heat. Season the beef with salt and pepper. Add beef to pan and brown all over, about 2 minutes per side.
While the beef is browning, add the cayenne, cumin, smoked paprika, garlic, onion, beef stock, tomato paste, jalapeno and lime juice to the slow cooker and stir to combine.
Transfer the beef to the slow cooker and cook on low for 6-8 hours or high for 3-4 hours.
Shred the beef with two forks and toss to coat with the juices.
Dish and serve hot with tortillas and your favorite toppings. Enjoy!