Steak, kidney, ale and mushroom pie

Source: Great Housekeeping (I think)

Notes: "A rich and satisfying pie. Even if you are not keen on kidney, try to incorporate a little, as it makes the gravy rich and thick, but it's not the end of the world if you omit it."

Prep time: 45 minutes
Cooking time: 3 hours
Servings 6

25g (1oz) unsalted butter
2 tbsp vegetable oil
900g (2lb) braising steak, cut into 2.5 cm cubes
3 lamb's kidneys, cut into small dice
3 tbsp plain flour, seasoned
2 onions, peeled and finely chopped
2 garlic cloves, peeled and chopped
1 x 500ml (18fl oz) dark ale, such as Black Sheep Ale
1 1/2 tbsp Worcestershire sauce
100g (4oz) chestnut mushrooms, quartered
375g (13oz) puff pastry
1 egg yolk, slightly beaten

• Preheat oven to 160 C, 140 fan, 315 F
• Heat the butter and oil in a frying pan. Toss the meat in the seasoned flour and brown a few pieces at a time, then transfer to a casserole. Continue until all the meat is browned. Add onions and garlic to the pan and cook for 10 minutes until soft and lightly coloured, then add to the casserole
• Add the ale and Worcestershire sauce, and season well. Place a lid on top and cook in the oven for 2 to 2 1/2 hours or until the meat is tender. Add the mushrooms, stir and pour into the pie dish. Put the pie funnel in the center and cool.
• Increase the oven to 200C, 180 fan, 400 F. (The cooked meat mixture can be frozen for up to a month)
• Grease the rim of the pie dish. Roll out the puff pastry on a lightly floured board. Cut a 2.5cm strip of pastry and press onto the rim of the pie dish. Brush the pastry rim with water. Roll the remaining pastry to make a lid and place on top of the pie, pressing down the edges. Trim and knock up by using a flat-bladed knife and horizontally tapping the edge
• Mix the egg yolk with a little water and brush over the pastry
• Place in the oven and cook for 25 to 30 minutes or until the pastry is risen and golden brown.