01. Start by boiling the potatoes in salted water until soft, about 15-20 minutes. Drain and mash with the cream or milk, then set aside. In a pan, sauté the chopped onion and shredded cabbage in butter or olive oil over medium heat until softened, around 5-7 minutes. Combine the mashed potatoes, cabbage mixture, grated cheese, mustard (if using), caraway seeds, salt, and pepper in a large bowl. Stir well and set aside to cool.

02. In a mixing bowl, combine the flour and salt. Add the shortening, butter (or margarine), and use your fingers or a pastry cutter to rub them into the flour until the mixture resembles breadcrumbs. Add the water, egg, and apple cider vinegar, and mix to form a dough. Knead lightly on a floured surface until smooth. Divide the dough into two portions: one for the base and one for the top. Roll out the first portion to line the base of your baking dish or air fryer-safe pan.

03. Preheat your air fryer to 180°C (360°F). Roll out the second portion of dough to cover the pie. Place the prepared filling into the pastry-lined pan, pressing it down gently. Lay the top pastry over the filling and seal the edges by pinching the dough together. Brush the top with the beaten egg for a golden finish.

04. Place the assembled pie into the air fryer basket. Cook at 180°C (360°F) for about 35 minutes or until the pastry is golden brown and crispy. You may need to check halfway through and adjust the cooking time depending on your air fryer model.