Preheat the oven to 200°C. Line a baking tray with nonstick baking paper. Heat the sunflower oil over a moderate heat and brown the beef mince all over; roughly 5 minutes. Stir in the chopped tomatoes and seasoning and bring to a simmer.
Simmer for 15 minutes, then remove from the heat. Transfer to a mixing bowl, stir in the cheese and allow it to cool set over a bowl of iced water, stirring occasionally. Lay the pastry on a lightly floured surface and cut into 4 equal rectangles.
Spoon the cooled filling evenly onto the bottom half of the pastry as you look at it. Spread into an even layer so that it reaches halfway up the pastry; leave a 1 inch border around the bottom edge and the sides.
Brush the border with the beaten egg, then fold the top half of the pastry over the filling and secure against the brushed pastry border. Transfer to the baking tray.
Make a few diagonal indentations in the top of the pastry and brush all over with the rest of the beaten egg. Bake for 20-25 minutes until golden and risen. Remove when ready and serve immediately.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.