Cut the braising steak into chunky pieces, each around 4–5cm/1½–2in. Trim off any really hard fat or sinew. Season the beef really well with salt and pepper.
Fry the beef in three batches over a medium–high heat until nicely browned on all sides, turning every now and then and adding more oil if necessary. As soon as the beef is browned, transfer to a large ovenproof dish .
Preheat the oven to 160c fry the bacon for 2–3 minutes, or until the fat crisps and browns. Scatter the bacon over the meat. Add a touch more oil to the frying pan and fry the chopped onion over a low heat for 5–6 minutes, stirring often until softened. Stir the garlic into the pan and cook for 1 minute more.Add the onion and garlic to the pan with the meat and pour over the wine. Stir in the tomato purée and 150ml water. Crumble over the stock cube, add the herbs and bring to a simmer. Stir well, cover with a lid and transfer to the oven.
Cook for 1½ –1¾ hours, or until the beef is almost completely tender.
Peel and fry off the onions in a little butter, then add the chopped mushrooms and allow to colour, add these to the beef mix and cook for a further 30 minutes.
Remove from the oven and check the beef is tender and falling apart, mix the corn flour with a little cold water to form a paste, stir this into the casserole to thicken the sauce.
Serve with mashed potato and sautéed greens