Beef and Mustard Pie

Preheat your oven to a gentle 150°C (300°F/Gas mark 2) to prepare for slow cooking the beef. In a large bowl, toss the beef chunks with the plain flour, seasoning generously with salt and freshly ground black pepper. This flour coating helps thicken the rich sauce later on. Heat a large casserole dish over medium-high heat until it’s nice and hot. Pour in half of the rapeseed oil, then add enough beef to cover the bottom without overcrowding. Brown the beef on each side until it develops a beautiful caramelized crust, then transfer it to a plate to rest. Repeat this process with the remaining oil and beef, ensuring each batch is well browned. Return all the browned beef to the casserole. Pour in the red wine, letting it bubble gently until the liquid reduces by half, concentrating the flavors. Next, add the beef stock, finely sliced onion, chopped carrots, fresh thyme sprigs, and the mustard to the pot. Give everything a good stir, then season well with additional salt and pepper. Place the lid on the casserole and slide it into the oven. Let it cook low and slow for about two hours, allowing the beef to become melt-in-your-mouth tender. Once cooked, remove the casserole from the oven and taste to adjust seasoning as needed. Remove the thyme sprigs and set the filling aside to cool slightly before assembling the pie. When ready, increase the oven temperature to 200°C (400°F/Gas mark 6). Transfer the cooled beef mixture into a pie dish. Brush the rim of the dish with the beaten egg yolks — this helps seal the pastry. Lay the puff pastry smoothly over the top of the filling. Brush the pastry surface generously with more beaten egg yolk to encourage a rich golden color as it bakes. Trim the edges of the pastry to leave just enough excess to crimp neatly, creating a decorative seal. Bake the pie in the oven for 30 minutes, or until the puff pastry puffs up gorgeously and turns a deep golden-brown. Meanwhile, prepare the green beans. Bring a saucepan of salted water to a boil, then add the beans. Cook for 4-5 minutes until they turn tender yet crisp. Drain the beans well and toss them with the butter until melted and well-coated. Season with freshly ground black pepper to taste. To serve, spoon a hearty portion of the beef and mustard pie onto each plate alongside a serving of the buttery green beans. Enjoy this comforting and flavorful meal that's perfect for any cozy dinner.