Preheat the oven to 160°C.
Heat the oil in an ovenproof casserole.
Dust the meat with the flour and fry until browned.
Transfer the beef to a plate.
Reduce the temperature and add the butter, onions and fry for 2 minutes.
Add the red pepper and cook gently for 4 - 5 minutes.
Stir in the paprika, tomato paste, tomato pureé and beef stock.
Cover and cook in the oven for 1½ hours, or until the beef is tender.
Remove from the oven, season with salt and pepper and skim any fat from the surface.
Stir in the sour cream.
To serve, drizzle the fresh cream over the casserole and sprinkle the additional paprika over the top.