Preheat the oven to gas 6, 200°C, fan 180°C.
In a bowl, mix together the steak, potato, onion, olive oil and Worcestershire sauce – if using. Season well.
Unroll the pastry and cut out 4 circles approx. 14-15cm (6in) in diameter – about the size of a small bowl. Place on nonstick baking paper on a baking tray.
Divide the steak mixture between the circles of pastry, heaping it on one side, and brush around the edge with the beaten egg. Fold the pastry over to cover the filling, then crimp with a fork to seal the edges. Put in the fridge to chill for 5-10 minutes.
Brush the pasties with the beaten egg and bake for 15 minutes until golden brown. Then turn the oven down to gas 3, 160°C, fan 140°C, and bake for a further 15 minutes. Leave to cool a little before serving.
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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.