Fold the long
sides of the pastry over the steak, tucking in and tightly sealing all the edges so the juice doesn't escape.
Cut 1/2 inch strip from
each side of pastry forming a 13x10 rectangle; reserve strips for sides.
FYI, if you guys are going to use puff pastry do not let the egg wash touch
the sides of the pastry.
Bring up
the sides of the pastry to form a firm seal along the top of the pasty, and use your fingers to crimp a wavy line along the seal.
Brush mixture over top and
sides of pastry.
Tuck
the sides of the pastry down into the casserole.
Brush the beaten egg on the top and
sides of the pastry.
Pull
the sides of the pastry towards the centre, leaving the centre exposed to the filling, brush the edges with melted butter and bake on high heat (400 F) for 20 minutes.
Arrange the berries neatly over the top and fold
the sides of the pastry up to cover the berries, pleating where necessary.