Heat oven to 220°C. Heat half the oil in a non-stick frying pan. Tip in the onions and cook until soft and golden, about 8-10 minutes.
Meanwhile, boil the potato cubes for 5 minutes, until just tender then drain. Tip into the softened onions and fry for 2 minutes more. Stir in the curry paste and cook for 2 minutes. Pop in the peas, plus 1 tbsp water. Cook for 1 minute, give everything a good mix and season. Tip into a bowl to allow to cool slightly.
Brush half the filo half-sheets with some of the remaining oil then lay the remaining sheets on top so you have 4 x double layers. Spoon a ¼ of the potato mix along one edge of each, leaving a bit of space at each end. Fold in the ends then roll up to seal (like a spring roll). Place seam-side down on a baking sheet, brush with the remaining oil and bake for 20 minutes, or until crisp.
Serve warm with a dollop of mango chutney and a tomato & onion salad, if you like.
