A golden suet pastry encasing a savoury filling of molten cheese, sticky caramelised balsamic onions, rocket leaves and pine nuts. Just add a large bowl of salad.
Start the filling. Heat the oil in a small, heavy-based pan, then add the butter and stir in the onions. Cover and cook over a very low heat, stirring occasionally, for about 20 minutes, until the onions are transparent and very soft.
Stir in the vinegar and sugar, then cover and cook for another 15 minutes, stirring occasionally. Uncover and leave to bubble until the mixture is very thick and all the moisture has boiled away. Season with salt and pepper, then remove from the heat and leave to go cold.
Dry fry the pine nuts over a low heat until golden, then leave to cool. Heat the oven to 220°C/200°C fan/425°F/Gas 7.
Make the pastry. Sift the flour and salt into a large bowl, add the suet and mix well. Add the butter, toss to coat in the flour, then gently rub in until the mixture resembles fine crumbs. Make a well, then stir in enough ice-cold water to make a soft but not sticky dough.
Turn out the dough onto a lightly floured worktop and knead gently until smooth. Divide the dough into 4 equal portions.
Roll out 1 portion to a rectangle 17 x 29cm. Use the pizza cutter and ruler to trim to a 16 x 28cm rectangle. Brush a 1cm strip all around the edges of the rectangle with the beaten egg.
Layer the filling. Arrange one quarter of the rocket down the centre of the rectangle, leaving the borders clear, then top with a quarter of the sliced cheese, then a quarter of the caramelised onion, then finally scatter with pine nuts.
Fold the short ends of the rectangle over the filling, then fold one long side of pastry over the filling to completely enclose (as if making a sausage roll). Pinch the pastry to seal.
Transfer to the lined baking sheet and brush with beaten egg to glaze. Prick the top with a fork or make a few cuts with a knife, for air holes. Repeat with the other 3 portions of dough and filling.
Bake for 15 minutes, then reduce the temperature to 200°C/180°C fan/350°F/Gas 4 and bake for a further 20 minutes, or until the pastry is crisp and golden brown. Serve hot.