1 tbsp olive oil
500g/1lb 2oz beef braising steak, cut into chunks
1 onion, roughly chopped
250g pack oyster mushrooms, sliced if large
1 tbsp tomato paste
1 tbsp fl our
100ml/31⁄2fl oz red wine
200ml/7fl oz hot beef stock, from a cube
350g/12oz potato, peeled
25g/1oz butter, chopped into small pieces
Heat oil in a non-stick pan over a high heat. Add beef and cook for 10 mins until browned all over, then remove from pan. Cook onion for 7 mins until softened. Stir through mushrooms, then cook for 3 mins more until golden. Stir in tomato paste and fl our and cook for 1 min more. Pour in wine and beef stock, bring to a simmer. Add beef back to pan. Cook, uncovered, over a gentle heat for around 2 hrs until meat is really tender, topping up with water if needed. Pour mixture into a 2 litre baking dish.
Heat oven to 190C/fan 170C/gas 5 and bring a pan of lightly salted water to the boil. Cook the potatoes for 10 mins until beginning to soften. Cool under a running tap, then coarsely grate. Sprinkle over the beef and dot with butter. Pop in the oven and cook for 30 mins until the crust is nice and crispy.