Combine the Spice Mix ingredients in a bowl. Sprinkle 4 teaspoons over the beef and pat so it sticks.
Heat the olive oil in a large heavy based pot over high heat. (Sauté function on instant pot) Add the beef (in batches if necessary) and brown well on all sides. Remove onto a plate.
Turn the stove down to medium. If the pot looks dry, add more olive oil.
Add the garlic and onion and cook for 3 minutes until soft.
Add the orange juice and lime juice, and scrape the bottom of the pot so the brown bits mix into the liquid.
Add tomato, beef stock, water and remaining spice mix. Mix, then return beef into pot.
Put the lid on, bring to a simmer then turn the stove down so it is bubbling gently, not rapidly. (Simmer function on instant pot)
Cook for 2 hours, then remove lid and simmer for another 30 minutes until beef is tender enough to shred.
Remove the beef from sauce, shred with 2 forks.
Leave the sauce to simmer with the lid off for 10 to 15 minutes to reduce and thicken to your taste. Adjust salt to taste.
Toss beef back into the sauce.
Transfer beef into large dish and serve.
