Chop the onion and mushrooms, add to the minced beef along with the mixed herbs and fry in a wok until mince is nicely browned.
Add the peas, carrots and stock cube and cook for a further 10 minutes. The filling is now ready for the pie.
To make the pastry, sieve the flour into a bowl and add the suet and baking soda. Finely chop the fresh rosemary and add to pastry mix. Thoroughly mix these ingredients and then add just enough water to form the pastry into a dough. Put in the fridge for 30 minutes.
Preheat oven to 200 C / Gas 6.
Form the pastry into 2 equal balls and flatten with the heel of your hand. They can then be rolled out to form two circles, slightly bigger than a 23cm (9 in) pie dish.
Grease the dish well, so that the pie does not stick, and then lay a circle of pastry over it. Trim back to edge of dish and then brush with beaten egg.
Blind bake in pre-heated oven for 10 minutes, this will stop the bottom of the pie going soggy.
Keep oven at 200 C / Gas 6.
Remove from oven and form a mound with the filling allowing a 1cm gap around the edge. Brush this gap with beaten egg. Lay the other circle of pastry over the top, pressing down gently around the edge. Trim back with a knife and your pie is almost finished.
Using the tip of a teaspoon or knife handle, crimp around the edge, this helps to stick the two pieces of pastry together and it also improves the appearance of your pie. Put a couple of small steam holes in the top and brush with beaten egg. The pie is now ready for the oven.
Bake in the centre of the oven for about 15 to 20 minutes until golden brown.
I have cooked this pie on many occasions and it looks and tastes just like grandma's used to. I usually have it without any accompaniments apart from a rich thick gravy. If you like old fashioned food, you'll love this!