- Preheat the oven to 200ºC fan oven/2201. ºC/gas 7. Grease a large casserole dish.
- Put the cubed potatoes on a baking tray and sprinkle the tablespoon of oil over. Season with salt and pepper and distribute the oil evenly with your hands.
- Heat a little oil in a large pan or wok. Add the onions and garlic and fry for 1 minute. Add the celery and sweet potatoes and fry for 1 minute.
- Add the pork mince and fry until the meat is no longer pink.
- Add the flour and cook for 1 minute, stirring frequently.
- Add the cider, stock, thyme and water. Season well with salt and pepper. Bring to the boil and the sauce should thicken. Turn down to simmer, for 10 minutes, with a lid on the pan.
- Put the potatoes in the oven for 30–35 minutes.
- Pour the pork mixture into the casserole dish. Unroll the pastry and place over the top of the pork. Brush the top with beaten egg. Pierce a hole in the centre to let out the steam.
- Place in the oven for 25 minutes, until the pastry is cooked and browned on top. Serve with the potatoes and green veg.