directions

1. Sieve the flours into a large mixing bowl and rub in the butter until crumbly. Stir in the water until it comes together as a dough. Shape into a disc, wrap in cling film and refrigerate for at least 30 minutes.
2. Preheat the oven to 220˚C/200˚C fan/gas mark 7 and line a baking tray with parchment paper.
3. Add the plums, berries, sugar and flour to a bowl and toss gently to combine. Leave to sit for 15 minutes, then drain off any excess liquid.
4. Roll out the dough on floured work surface into a large circle, about 30cm in diameter. Use the rolling pin to transfer it to the baking tray.
5. Pile the fruit mixture into the centre of the dough, leaving a 6cm border around the sides. Fold over the sides of the pastry to make a crust — most the fruit filling should still be exposed.
6. Brush the crust with the beaten egg and sprinkle over some extra demerara sugar. Bake for 35-40 minutes until the pastry is deep golden brown and the fruit is soft. Serve warm or at room temperature with ice cream.