- ½ cup caster sugar
- ¼ cup cornflour
- 300g raspberries
- 250g blueberries
- 200g blackberries or mulberries
- 2 tablespoons milk
- 1–2 teaspoons raw sugar
- 2¼ cups plain flour
- 1/3 cup pure icing sugar, sifted
- 185g cold butter, chopped
- 1 egg yolk
- 1–2 tablespoons chilled water
To make pastry, place flour, icing sugar and butter in a food processor and process until mixture resembles fine crumbs. With motor running, add egg yolk and 1 tablespoon of chilled water, and process until pastry comes together into a ball. (Add more chilled water, if necessary.) Turn pastry onto a lightly floured surface and gently knead until smooth. Shape into a disc and wrap in plastic wrap. Place in refrigerator for 30 minutes to rest.
Preheat oven to 180°C. Combine caster sugar and cornflour in a large bowl. Add raspberries, blueberries and blackberries and gently stir to combine.
Lightly grease a 4cm-deep 20cm (base measurement) round pie dish. Roll out pastry between 2 sheets of baking paper until 3mm thick. Line pie dish with pastry and trim excess. Roll out offcuts into a 25cm disc. Cut into 1.5cm-wide strips. Spoon berry mixture into pastry case. Brush edge of pastry case with milk. Arrange pastry strips in a lattice pattern over pie. Brush edge of pastry case with milk. Press remaining pastry strips around edge of pastry case. Press firmly to seal. Using floured fingers, pinch edge of pastry to crimp. Brush with milk and sprinkle with raw sugar.
Line a baking tray with foil (to catch any juices). Place pie dish on prepared tray. Loosely cover edge of pie with foil to prevent over-browning. Bake for 30 minutes, then remove foil. Bake for a further 25–30 minutes or until pastry is golden and filling is bubbling. Cool on a wire rack.