Heat 1 tbsp of the oil in an ovenproof casserole dish or pot and fry onion and celery for 10 minutes, or until softened. Add the paprika and sizzle for 2 minutes, then add the beef and stir to coat. Preheat the oven to gas 3, 160ºC, fan.
Add the chopped tomatoes, tomato purée, beef stock and peppers. Cover the pot and cook in the oven for 2 hours, until the meat is tender and the sauce is rich and dark. Season. Put the remaining oil in a pan and fry the chestnut mushrooms over a high heat for about 4 minutes, until golden.
Scatter over the stew, along with the parsley. Serve with baked potatoes, pasta or rice, topped with dollops of soured cream or yogurt.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.