Preheat the oven to 200ºC/fan 180ºC/gas mark 6. Heat the oil in a small pan and add the onion. Cook until soft, then add the carrot and apple. Transfer to a bowl, then mix in the sage and pork mince until well combined.
Unroll the ready-rolled puff pastry, then cut in half lengthways. Divide the apple and carrot mixture in two, and place in the middle of each strip of pastry. Brush all edges of the pastry with the beaten egg, reserving some for the top. Fold the pastry over the filling, and seal by pressing gently on each roll.
Flip the roll so the seal is on the underside of each roll. Cut each strip into 8 rolls. Brush the tops with the remaining beaten egg, then sprinkle with the poppy and sesame seeds. Place the rolls on a baking tray and bake for 25-30 minutes until crisp and golden, and the pork is cooked through.