Add oil to a pan and brown the meat quickly and evenly (making sure the pan is quite hot).
Add browned beef, onion, beef stock, garlic, fresh chilli, tomato paste, white vinegar, Worcestershire Sauce and remaining dried spices to the slow cooker. Cook, covered on low for 6 hours.
Remove the beef only from the cooker and shred the meat coarsely using two forks.
Return the meat to the slow cooker and continue to cook, covered on low for a further 30 minutes.
• Serve shredded beef on tortillas (draining if needed), sprinkle with fresh coriander. Add grated cheese, diced tomatoes, shredded lettuce, avocado and sour cream.
Recipe by Mrs Organised at http://www.mrsorganised.com.au/2014/12/06/shredded-beef-tortillas/