Heat the sunflower oil in a wok and add the onion, garlic, ginger and chilli. Stir-fry over a medium heat for 2–3 minutes and then add the curry powder and minced chicken. Stir-fry over a high heat for a further 4–5 minutes or until the meat is browned and just cooked through.
Transfer the mixture to a bowl and add the mashed potato and coriander and stir to mix well. Season and set aside.
Use a 7.5 cm (3 inch) cutter to make 8 rounds of puff pastry. Place a large spoonful of the mince mixture into the centre of each pastry round. Brush around the edges of the pastry with the beaten egg, then fold the pastry over to enclose the filling. Using the tines of a fork, press and crimp the edges to seal.
Pour sunflower oil into a wok until one-third full and heat to 180–190°C (350–375°F), or until a cube of bread browns in 30 seconds. Deep-fry the puffs in batches for 2–3 minutes or until puffed up and golden. Drain on kitchen paper and serve immediately with tomato ketchup, if liked.