Add a good drizzle of oil to a large pot over medium-high heat and add your meatballs. Fry them until they get a nice crust on them, turning regularly. You don't need to cook them right through at this point, just ensure they caramelize and brown. Remove from pan and drain excess fat if needed (around 1 tbsp left is fine and will add flavour).
Turn heat down to medium and add in your onion into the oil/fat. Fry until they begin to turn golden, then add in sun dried tomatoes and garlic. Continue frying for 1-2 more minutes until the tomatoes soften and the garlic browns, then add in your tomato puree. Fry for a minute or so, then pour in your passata.
Wash out the jar with a little water, then pour in beef stock and Worcestershire sauce. Add in parsley, oregano, chilli flakes, salt, pepper and a good pinch of sugar (to taste). Give it a stir and deglaze the pot with your wooden spoon. Add your meatballs back in, give it one final stir, turn the heat to low then pop on the lid and simmer for 30-45mins. This will allow the meatballs to become soft and juicy, it'll also allow them release flavour into the sauce. If you're pushed for time even 10-15mins will help, just ensure you keep a heavy lid on so the sauce doesn't reduce.
Take off the lid, pour in your rice and give it all a good stir. Pop the lid back on and simmer for 15mins, or until the rice is cooked through, stirring occasionally. If you over reduce just add in a splash of water to help the rice cook through if needed.
Serve up with extra parsley and a good helping of parmesan!