Preheat the oven to 170ºC/350ºF/Gas 3.

Place the cubes of steak into a large, strong plastic bag and the kidney pieces into another bag. Divide the flour between the two bags, then season, to taste, with salt and freshly ground black pepper. Tie the ends of the bags and shake until the steak and kidneys are thoroughly coated in the seasoned flour.

Heat two tablespoons of the oil in a large non-stick frying pan and fry the steak, in batches, over a medium heat, adding extra oil as needed, until the steak is well-browned all over. Remove the steak from the frying pan with a slotted spoon and transfer to a flameproof casserole.

Return the frying pan to the heat and repeat the process with the kidneys, frying on both sides until well-browned. Remove the kidneys from the frying pan with a slotted spoon and transfer to the casserole.

Return the frying pan to the heat, add the remaining oil, then add the onion. Cook the onion over a low heat, stirring often, for five minutes, or until softened. Stir the cooked onion into the casserole with the beef and kidneys.

Deglaze the frying pan with the wine, bringing it to the boil while stirring to lift all the browned bits from the bottom of the pan. Pour the mixture immediately over the beef, kidneys and onion.

Strip the thyme leaves from the stalks and add them to the casserole. Stir in the bay leaf, beef stock and tomato purée.

Bring the beef mixture to the boil. Remove three ladlefuls of the sauce for gravy and set aside in a small pan to cool. When cooled, set it aside in the fridge for use as gravy.

Meanwhile, for the suet pastry, put the flour, suet and salt into a large bowl and mix until well combined.

Spoon the steak and kidney mixture into the pastry-lined pudding basin. Brush the rim of the pastry with water. Roll the remaining pastry into a circle just large enough to sit on top of the pudding dish and place it over the filling. Trim into place and press the edges together well to seal.

Cover the dish with a large circle of baking parchment, with a pleat in the middle to allow for expansion. Cover the parchment with a circle of aluminium foil, again with a pleat. Secure both covers tightly with string. Create a carrying handle by tying the excess string across the top of the basin - this will help you lift the pudding out of the pan after it's cooked.

When the pudding is cooked through, turn off the heat and carefully lift the basin from the water. Let the pudding stand for five minutes.

Heat the reserved gravy on the hob, stirring, until the gravy is bubbling and heated through. Strain through a small sieve into a warmed jug.

Cut the string, foil and paper off the pudding basin. Run a blunt-ended knife around the inside of the pudding basin to loosen the sides of the pudding and invert it onto a deep plate. Serve in generous wedges with hot gravy.