Place the seasoned flour on a baking sheet and add the diced beef. Using your fingers, toss the beef in the seasoned flour until it's completely covered.
Place a skillet over medium heat and add the oil, onions, flour coated beef, kidneys, English bitter and beef stock. Cook for about 5 minutes. Reduce heat and add the tomato puree, salt and pepper and fresh marjoram. Stir the ingredients. Simmer until the meat is tender and the stock has thickened to a gravy-like consistency. Ideally, cool and put in the fridge over night to enhance the flavor.
Pre-heat oven to 325 degrees F. Roll out the puff pastry. Sprinkle pepper on the bottom of the baking dish and scoop in the steak and kidney mixture. Spread pastry over the meat mixture and trim any excess that is hanging over the side of the dish. Pinch the pastry to the side of the baking dish. Combine the egg and milk together in a bowl. Brush this mixture on top of the puff pastry.
Bake for 30-40 minutes. Serve hot. To plate: Make sure you have a hot plate on your table before you place this dish down. Garnish with remaining fresh marjoram.