Turn the heat up to medium and stir in the beef mince, breaking it up with a wooden spoon. Cook for around 5 minutes, or until browned all over. Add the wine and crushed stock cube. Keep stirring until the liquid has completely reduced. Add the tomatoes and 400 ml of water. Bring to the boil. Reduce to a simmer, cover and cook for around 1 hour. Now, remove the lid and continue cooking for 30 minutes, or until sauce has thickened.