Chop onion, carrot and celery, mince garlic and chop rosemary. Alternatively you can use a food processor and pulse everything until the vegetables look minced but not too finely. Set aside till needed.
Remove extra fat off the short ribs if too fatty, season with salt and sear them with 1 tbsp of olive oil on all sides till golden brown. Remove from the pan. Add the previously chopped vegetables and rosemary with the remaining tablespoon of olive oil and sauté them over low heat for 7-10 minutes.
Add the sautéed vegetables to the bottom of a large dutch oven or a deep casserole dish, then add the canned chopped tomatoes or passata, red wine, water and salt, mix to combine and top with seared short ribs, cover with a lid and cook in the preheat to 160C/325F for 3.5 hours.
Check on them half way through, flip the short ribs over and add a splash of water if the sauce is getting too low. Put back in the oven and continue cooking until the meat falls of the bones. Remove the bones and shred the meat with two forks directly in the pot. Mix well to combine.
Before serving the ragu get a pot of water boiling and cook 500g / 1 lbs of favourite pasta, shred the beef with two forks and mix into the sauce.
Once the pasta is al dente mix into the sauce and serve sprinkled with Parmesan cheese.