Steak and Kidney Pie with Bacon and Mushrooms

Prepare the Meat Filling: Dice the beef kidney and stew meat. In a large pot or Dutch oven, heat the vegetable oil over medium-high heat. Season the flour with salt and pepper. Toss the kidney and stew meat in the seasoned flour, shaking off excess. Sear the meat in batches until browned on all sides, then remove from the pot. (15 minutes)

Sauté Aromatics and Deglaze: Add the diced bacon to the pot and cook until crisp. Add the chopped onion and sliced mushrooms, cooking until softened. Pour in the beef stock and red wine, scraping up any browned bits from the bottom of the pot. (10 minutes)

Simmer the Filling: Return the browned meat to the pot. Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 1 1/2 to 2 hours, or until the meat is very tender. Remove from heat and let cool slightly. (90-120 minutes)

Prepare the Mashed Potato Topping: While the meat is simmering, place the cubed potatoes in a saucepan and cover with water. Bring to a boil, then reduce heat and simmer until tender, about 20 minutes. Drain well and mash with butter and milk until smooth and creamy. Season with salt and pepper. Allow to cool slightly. (30 minutes)

Assemble the Pie: Preheat oven to 375°F (190°C). Press one sheet of puff pastry into a 9-inch pie dish, trimming the edges to fit. Fill the pie with the cooled meat mixture. Spread the mashed potatoes evenly over the top of the meat, about 1-inch thick. (20 minutes)

Top and Bake: Place the remaining sheet of puff pastry over the top of the pie. Trim the excess pastry around the edges and crimp or flute the edges to seal. Brush the top of the pastry with the beaten egg wash. Cut a few slits in the top to allow steam to escape. (10 minutes)

Bake in the preheated oven for 20 to 25 minutes, or until the crust is golden brown and the filling is bubbly. Let cool slightly before serving. (20-25 minutes)