Cheese and onion pasties

Method

1. To make the pastry, put the flour and salt in a mixing bowl. Rub in the cubed butter between your thumbs and forefingers until the mixture resembles fine breadcrumbs. Stir in the egg, milk, and vinegar using a table knife. Using your hands, work the mixture until it comes together to form a dough – it should be soft but not sticky. Shape the dough into a ball on a flour-dusted work surface, flatten into a disc and cover in cling film. Set aside in the fridge for at least 30 minutes to rest (see Make Ahead).
2. For the filling, melt the butter in a heavy-bottomed pan over medium heat. Add the onions and cook, covered for 10 minutes until softened. Stir regularly and add a little water if they start to look dry. Add the potato to the onions and continue to cook for 5-10 minutes. Remove from the heat and set aside to cool.
3. Heat the oven to 180ºC fan/gas 6. Divide the pastry into 4 equal pieces. Roll out one piece on a lightly floured surface to form a circle roughly 4-5mm thick (keep the rest of the pastry wrapped in the fridge).
4. Stir the cheddar and cream (if using) through the cooled potato mixture, season with a good pinch of salt and lots of freshly ground black pepper (you want the mix to be heavily seasoned). Pile a quarter of the cooled filling on one half of the pastry, leaving a 3cm border around the edge. Brush the edges with a little beaten egg, then fold the other half over and press to enclose the filling. Crimp the edges of the pastry and place on a large, lined baking sheet. Repeat with the remaining pastry and filling. Brush the pasties with the egg, poke with a fork so steam can escape, then bake for 25-30 minutes until golden (see Make Ahead)
5. Serve the pasties, hot from the oven with chips and baked beans, or your favourite pickle if you like.