Chop mushrooms and steak into similar sized chunks, depending on how chunky you want your pie filling to be.
In a large saucepan add a small amount of oil and brown the meat, mushrooms and onions.
When all the ingredients in the saucepan are browned add the 4 stock cubes and mix together, then add the water and season with salt and pepper.
Bring to the boil then simmer with the lid on for aproximately 1 hour
When the filling is cooked, roll out your pastry to fit the bottom of your greased pie dish (not too thick or it won’t cook) and prick a few holes in the bottom with a fork so the air can escape, Then add your filling using a slotted spoon, spoon over as much pf the gravy as you want, then roll out some more pastry to cover the top of the pie.
Beat together the egg with some water and use the eggwash to brush over the pie, this gives the pie a shiny and golden finish when it is cooked.
Place into an oven preheated to 220 degrees C for 30 minutes or untill the top is a deep golden brown and crusty.
For the gravy : Mix togther the cornflour and the cold water till it makes a thin paste.
Using the remaining cooking liquid from the filling and on a medium heat add the cornflour mixure a bit at a time wilst stirring. Keep adding untill you get your desired thickness.
