Heat oven to 180C/160C fan/gas 4. Make the pastry by rubbing the lard or margarine into the flour and mixing to a dough with a little water – it’ll take 2-3 tsp. Roll out half the pastry and use it to line a 22cm flan or tart tin. Layer the potatoes, onion, bacon and seasoning into the pastry case, then pour over the egg (saving a little to glaze the top).

Roll out the remaining pastry, cover the pie and trim the edges. Brush with the remaining beaten egg. Bake for about 45 mins to 1 hr, until the pastry is golden brown and a knife can be easily inserted into the tender potatoes.