Preheat oven to 180C (160C fan forced). Heat oil in a large Dutch oven over medium-high heat. Season lamb shanks generously with salt and pepper all over and cook in batches in the pan for 5-6 minutes or until browned all over. Remove and set aside.
Reduce pan heat to medium low and add the onion, carrot, celery and garlic along with a big pinch of salt. Cook, staring often for 10 minutes or until softened. Add the thyme and stir to combine, then add the flour and cook, stirring for 1 minute. Add the tomato paste and cook for a further 1 minute. Add the bay leaves and rosemary.
Pour in the red wine and allow it to bubble up and thicken slightly. Cook for 2-3 minutes. Add the stock, water and tomatoes and bring to a simmer.
Return the lamb shanks to the pan, manoeuvring so they are mostly or fully covered in the liquid. (make sure the meaty end is at least pointing down into the liquid if your can’t cover them completely). Bring to a simmer, cover with a tight fitting lid and transfer to the oven. Bake for 2 hours.
Remove the lid and continue baking for a further 30 minutes or until the lamb is browned and very tender (almost falling from the bone).
Using tongs, remove the lamb shanks from the pot and set aside covered with foil. Also removed discard the bay leaves and rosemary sprig. Place the pan onto the stove and using an immersion blender (stick blender) puree the sauce until smooth. Taste and season with extra salta and pepper if required. Return the lamb shanks to the sauce and heat through for 5-10 minutes.
Serve the lamb shanks with mashed potato, steamed greens and a big spoonful of the sauce over the top. Garnish with chopped fresh parsley. Serve