Make pastry: Combine flours, baking powder, salt and butter in a food processor. Pulse, until the mixture is crumbly. Add the egg and process until ingredients barely cling together.

Knead pastry very lightly and divide into two flattened discs. Wrap each in plastic wrap and refrigerate for 30 minutes while preparing filling.

Meanwhile, make mince: Add the oil and onion, carrot, parsnip to a large frying pan, cook over high heat, stirring until softened and lightly golden. Add the beef and cook, stirring until browned.

Add the tomato paste, Worcestershire, soy sauce, cabbage and the white pepper and cook, stirring, for a further 5 minutes or until thickened slightly. Remove from heat to cool completely.

Preheat oven 180°C (160°C fan-forced). Grease an 18 x 26cm slice pan.

Roll out each pastry disc to form a rough 18 x 26cm rectangle. Press one pastry rectangle into the prepared tray. Spread the cold savoury mince mixture into the pan. Cover with the second piece of pastry. Brush with the beaten egg and bake for 30 minutes or until golden brown. Sprinkle with sea salt flakes.

Serve cut into large squares.