Heat 1 tablespoon of the oil in a large frying pan on the hob and fry the beef, in batches, until browned on all sides, draining each batch to a plate. Add the kidney to the pan and fry for a further 5 minutes; drain. Add the remaining oil, onion and mushrooms to the pan and fry gently for a further 5 minutes.
Return all the ingredients to the pan, including any juices from the beef, and sprinkle in the flour, stirring for 1 minute. Add the stock and ale, and bring to the boil. Season with salt and pepper, and transfer to a casserole dish. Cover with foil and place on the lower rack of the halogen oven.
Set the temperature to 200°C (392°F) and cook for about 50 minutes until the meat is tender. Check the seasoning and leave to cool.
Transfer the mixture to 4 individual pie dishes or one large dish, on the lower rack of the halogen oven. Do not fill each dish with liquid to more than 1.5 cm (¾ inch) from the top. Serve any excess in a jug.
Roll the pastry out on a lightly floured surface and cut out a lid or lids that are about 1 cm (½ inch) larger than stacking the dishes or dish. Position the pastry, crimping it around the edges to seal. Brush the pastry with beaten egg to glaze, sprinkle with a little salt and place on the lower rack of the halogen oven.
Set the temperature to 225°C (437°F) and cook for 25–30 minutes, covering the pastry with foil if it starts to brown too much. (If using one large dish, increase the cooking time to 35 minutes.) Serve with minted peas and sautéed potatoes.