Heat half the rapeseed oil and half the butter in a large heavy-based saucepan. Season the beef with salt and white pepper and brown for about 4 minutes in the hot fat. When coloured all over, sprinkle with the flour and cook, stirring the meat around until the pan becomes dry.
Add the vinegar and 2 tablespoons water and use these to deglaze the pan, scraping up any bits stuck to the bottom. Transfer to a flameproof casserole dish and add the tomatoes.
Clean the original pan and sauté the onions and carrots in the remaining oil and butter until the onions are soft and translucent. Tip into the casserole with the sugar, allspice and bay leaves. Pour in enough water to just cover the meat.
Bring to the boil, then reduce to a simmer and cook with the lid on for about 1 hour.
Stir the stew occasionally and halfway through cooking check the liquid level to see it has not dried out; top up if needed.
Slice the parsnip into thin rounds, put in a non-metallic bowl, pour over the pickling solution and leave to pickle for at least 20 minutes.
After the stew has been cooking for 35 minutes, get the potatoes on to boil and while they are cooking prepare the leek. Preheat the oven to 180°C (350°F). Rub the butter on a sheet of foil and place the leek, cut side down, on top. Wrap in the foil, place on a baking tray and cook in the oven for 15 minutes until deliciously soft.
Serve the stew with the boiled potatoes and the leeks, garnished with the chopped hazelnuts and drained parsnip slices.