First make the dough. Combine the flour and salt in a bowl. Make a well in the centre and add the melted butter and 5 tbsp. of warm water. Mix with a spoon to form a dough. Add a little extra water if the mixture seems too dry. Tip onto a lightly floured surface and knead for 5-10mins to a dough. Cover with cling film and leave to rest in a cool place for 30mins.
Meanwhile, prepare the filling. Add the oil a saucepan, fry the garlic and ginger for about 30 seconds. Add the onion and fry for around 3mins until slightly softened and caramelised. Add the par boiled potatoes, curry powder and remaining spices and season, cook for 2-3mins until the spices have cooked through.
Pour in the stock and cook for around 10mins or until the liquid has reduced. Remove from the heat and set aside to cool.
Preheat the oven to 200ºc / Gas 6. On a floured work surface, roll out the pastry so that the pastry is thin (not too thin) and with a round pastry cutter, cut out round pasties. Fill each with a tablespoon of the filling. Brush the pastry edges with egg, fold over the filling. Press the sides together with a fork to seal. Arrange the puffs on a baking sheet, brush with more egg and bake for 25mins.