My secret tip is spray oil, it’s so much easier than using a pastry brush (but a pastry brush is fine if you prefer). With a light touch - oil the tray and line with your first sheet of filo. Oil again and place your next sheet in the opposite direction. Continue this process with all of the pastry. Add the pie filling and wrap with the first sheet of pastry. Repeat the oiling process until all of the party wraps the pie. Turn over the pie and sprinkle with the onion seeds and a pinch of salt.