1. Preheat the Oven: Preheat your oven to 180°C (350°F)
2. Prepare the Meat: Toss the diced steak and kidneys in the plain flour, ensuring they are well-coated
3. Brown the Meat: Heat the vegetable oil in a large frying pan over medium-high heat. Add the steak and kidneys, and cook until browned on all sides. Remove the meat from the pan and set aside
4. Cook the Vegetables: In the same pan, add the chopped onion, garlic, carrots, and celery. Cook until the vegetables are softened, about 5-7 minutes
5. Combine Ingredients: Return the browned meat to the pan. Add the beef stock, red wine, Worcestershire sauce, thyme, rosemary, salt, and pepper. Stir well to combine
6. Simmer: Bring the mixture to a boil, then reduce the heat and let it simmer for about 30 minutes, or until the meat is tender and the sauce has thickened
7. Prepare the Pastry: Roll out the puff pastry on a lightly floured surface. Cut it to fit the top of your pie dish
8. Assemble the Pie: Transfer the meat mixture to a pie dish. Cover with the puff pastry, pressing the edges to seal. Make a few small cuts in the pastry to allow steam to escape
9. Glaze and Bake: Brush the top of the pastry with the beaten egg. Bake in the preheated oven for 25-30 minutes, or until the pastry is golden brown and crispy
10. Serve: Let the pie cool slightly before serving. Enjoy your luxury steak and kidney pie with a side of mashed potatoes or steamed vegetables
