Place a large pan with a good drizzle of oil on a high heat.
Throw in the beef and season well with sea salt and black pepper.
Cook, turning regularly, until browned all over. Transfer to a plate and set aside.
Pick the rosemary leaves, peel the onions and garlic, trim the celery and finely chop it all together. Add to the pan with the rosemary. Reduce the heat and soften for 5 minutes.
Pour in the wine, bring to the boil and let it bubble until reduced by half. Add the tinned tomatoes and stock, then return the beef to the pan.
Secure the lid, and leave to cook for 1 hour.
Meanwhile, make the polenta. In a medium saucepan, bring the milk to the boil with 700ml of water and a good pinch of salt.
Very slowly pour in the polenta in a thin stream, whisking constantly to avoid lumps. Stir for a few minutes until starting to thicken, then turn down the heat to low.
Cook for 30 minutes or so, stirring every 5 minutes, until thickened and coming away from the sides of the pan.
Stir through the butter, finely grate in the Parmesan and adjust the seasoning.
Break up the beef with a spoon and Spoon the polenta into bowls and serve topped with the stew.
