Heat the oil in a large pan over medium heat. Add the stewing beef and brown it on all sides. Do this in batches if necessary to avoid crowding the pan.

Add the kidneys to the pan and brown them as well. Cook for about 2-3 minutes, then transfer both the beef and kidneys to a plate.

In the same pan, add the chopped onions and garlic, cooking until soft and translucent (about 5 minutes).

Stir in the flour and cook for 1-2 minutes to get rid of the raw flour taste.

Gradually add the beef stock, stirring continuously to avoid lumps. Add Worcestershire sauce, tomato paste, salt, pepper, bay leaf, and thyme.

Return the beef and kidneys to the pan, reduce the heat, and let the mixture simmer for 1 hour, or until the meat is tender. Stir occasionally and add a little more water if necessary to keep the mixture moist.

Preheat your oven to 200°C (400°F).

Roll out the ready-made shortcrust pastry on a lightly floured surface to fit the size of your pie dish. You’ll need enough for the base and a lid.

For a steak and kidney pie, roll out the shortcrust pastry to a thickness of about 3-5 mm (1/8 inch). This ensures the pastry is sturdy enough to hold the filling without becoming too thick or doughy after baking. If you're using puff pastry for the top, you can aim for a similar thickness to ensure it bakes evenly and turns golden and flaky.

Line your pie dish with half of the pastry, making sure to press it into the edges. Leave a little overhang to seal the pie later.

Once the meat filling has cooked, remove the bay leaf and let it cool slightly.

Spoon the filling into the pastry-lined dish, ensuring it's evenly spread.

Roll out the remaining pastry and cover the top of the pie. Seal the edges by pressing down with a fork or your fingers, then trim any excess pastry.

Cut a small hole in the center of the pastry to allow steam to escape during baking.

Brush the top with the beaten egg to give it a golden finish.

Place the pie in the preheated oven and bake for 30-35 minutes or until the pastry is golden brown and crisp.

Let the pie cool for a few minutes, then serve with mashed potatoes and steamed vegetables.

If you're nervous about cleaning kidneys, you can buy them pre-prepped from the butcher.

For added convenience, you can use store-bought puff pastry for the top crust if you prefer a lighter pie.