Heat the oil in a pan, add the onion and cook for 5 mins. Add the garlic and beef, turn up the heat and cook until the meat is browned. Add the potato, half the turmeric, the purée and thyme, plus 200ml water. Cover and simmer for 15 mins, then remove the lid and cook for 5 mins more. Add the hot pepper sauce and leave to cool.
Heat oven to 220C/200C fan/gas 7. Roll out the pastry to the thickness of a £1 coin. Cut out 6 x 15cm circles, using a small plate as a guide. Divide the mince between the circles, piling it up on one side. Mix the egg with the remaining turmeric, brush around the edge of each circle, then fold over and use a fork to seal the edges. Arrange on a baking tray lined with baking parchment, brush with a little more egg and bake for 20-25 mins. Serve with a green salad.