Prepare the crust: In a food processor, combine the flour and salt. Add the cold butter and pulse until the mixture resembles coarse crumbs. Gradually add cold water, 1 tablespoon at a time, and pulse until the dough begins to come together. Turn the dough onto a lightly floured surface and knead it a few times to bring it together into a ball. Divide the dough into two portions—one slightly larger than the other—and wrap them in plastic wrap. Refrigerate for at least 30 minutes.

1. Make the filling: In a large skillet, heat a little oil over medium heat. Add the chopped onion and garlic, and sauté until softened, about 3-4 minutes. Add the ground beef (or meat mixture) and cook until browned, breaking it up with a spoon as it cooks. Drain excess fat if necessary.
2. Stir in the carrot, peas, beef broth, Worcestershire sauce, thyme, and rosemary. Bring to a simmer, then cook for 5-7 minutes until the mixture thickens slightly. Sprinkle in the flour and stir to combine. Cook for another 2 minutes to allow the flour to thicken the filling. Season with salt and pepper to taste. Remove from heat and let the filling cool slightly.
3. Assemble the pie: Preheat your oven to 375°F (190°C). Roll out the larger portion of dough on a floured surface to fit a 9-inch pie dish. Carefully transfer it to the dish, pressing the dough into the sides. Fill with the cooled meat mixture.
4. Roll out the second portion of dough and place it over the top of the pie. Trim any excess dough, and crimp the edges to seal. Cut a few small slits in the top to allow steam to escape. You can also brush the top of the pie with an egg wash (a beaten egg mixed with a little water) for a golden finish.
5. Bake: Place the pie in the oven and bake for 35-40 minutes, or until the crust is golden and flaky. If the edges start to brown too quickly, cover them with foil.
6. Serve: Allow the meat pie to cool for about 10 minutes before slicing and serving.