Heat the oil in a frying pan over a medium heat. Add the pork, onion and curry powder, season and cook for about 10 minutes until the pork is just cooked and the juices have evaporated from the pan. Add the potatoes and peas and mix well. Remove the pan from the heat, add the chopped herbs and set aside to cool.
Lay the filo pastry sheets in a stack on a clean board. Cut into quarters to give 4 rectangles from each sheet. Cover the pastry with a barely damp tea towel to prevent it drying out.
Lay one sheet of filo on the work surface with a short side nearest you. Place a dessertspoonful of the filling on the end nearest you and fold the bottom right corner of the pastry over to meet the left hand side and enclose the filling in a triangle. Continue folding the parcel over down the length of the pastry to make a neat triangular parcel. Brush the loose edge with a little of the beaten egg to seal, then place on a baking sheet. Repeat to make 20 samosas, then brush them with beaten egg and chill until ready to cook.
Preheat the oven to 220°C (425°F), Gas Mark 7. Lightly spray the samosas with cooking oil spray and cook for 12–15 minutes oven until golden brown. Serve warm.