MAKES FOUR INGREDIENTS
500g self-raising flour, plus extra for dusting
1 tsp salt
75g cold butter, diced
Up to 300ml ice-cold water
1-2 beaten egg yolks, for egg washing
Briefly pulse the flour, salt and suet together in a food processor until mixed. Add the butter and pulse until you have the texture of breadcrumbs.
With the processor running, add the water a bit at a time, until you have a dough that has formed together but is not too sticky. You might not need to add all of the water.
Turn the dough out on to a lightly floured surface and finish kneading with your hands. Divide it into four balls and wrap each one in cling film. Leave in the fridge for a couple of hours or overnight.
For the filling, gently heat half of the butter in a saucepan and sweat the onion for five minutes until soft. Add the leek and cook for another two minutes, adding a good pinch of salt.
Add the potato and apple and cook for 10-15 minutes or until they are soft. Add a few twists of black pepper.
When the mixture is cooked, add the gammon, sage leaves and the rest of the butter and stir them through. Allow to cool.
Preheat the oven to 220C/200C fan/Gas 7. Roll out the four balls of dough on a lightly floured surface into rectangles measuring about 23 x 15cm.
Divide the filling mixture into four and shape each portion into thin logs lengthways along the middle of each rectangle. Fold the pasty over, brushing the edges with a little iced water, crimp the edges to seal the pies in a rectangular shape.
Brush them lightly with the egg yolk and transfer to a baking sheet. Prick the top of each pie with a fork.
Bake for 10 minutes then turn the oven down to 200C/180C fan/Gas 6. They should be ready after another 25 minutes. Check the pastry is cooked through and golden brown.
Leave to cool before serving.