Fry the onion in the butter until it is browned. Remove it from the butter and set it aside. Remove any fat or gristle from the steak (and kidneys, if you're using them), toss the meat in the flour and saute it lightly in the butter. Transfer the meat to a casserole. Fry the mushrooms for 2 minutes and add them and the onion to the meat. Add the parsley, bayleaf and seasoning.
Mix the stock, Worcestershire sauce and tomato paste, and pour it over the meat. Cover and cook in the oven at 300F for one hour or until the meat is just tender. Remove and allow to cool. If the gravy is too thin, reduce it until it thickens.
Sift flour and salt into a mixing bowl; cut the butter and lard into pieces and rub them into the flour with your fingertips until the mixture resembles breadcrumbs. Stir in the sugar. Mix the egg yolk with the water and pour it into the flour. Mix quickly with a palette knife until it forms a dough. Knead lightly until the dough is smooth. Wrap it in wax paper and refrigerate for half an hour.
Preheat the oven to 450F. Roll out half the pastry to about 1/4 inch thickness and line a 9-inch pie dish with it. Put the filling on top of that, and then roll out the rest of the pastry to make a lid. Moisten the edges of the base before putting the lid on, then press down the edges of the lid with a fork and trim off any excess pastry.
Make a hole in the centre of the lid, brush the pie with milk and beaten egg, and bake at 450F for 20 minutes and then at 325F for another 30 minutes.
From the Dinner Co-op