Preheat the oven to 180°C.
Line a baking sheet with parchment paper.
In a bowl, place the plum pieces with caster sugar, corn flour and orange zest. Toss to coat the peaches.
On a lightly floured work surface, roll the pastry into an approximate circle about 20cm in diameter and 3mm thick.
In a bowl, combine the plums, sugar, orange zest and corn flour. Place over the pastry and drizzle with honey.
Tidy the pastry edges over the fruits and brush the edges with egg wash and an extra sprinkle of sugar and pistachios.
Place in the oven for 25 - 35 minutes until golden brown and the peaches are bubbling.
Remove from the oven, serve warm or at room temperature.