Method

• 1.
  To make the crust, place flour, pecan, caster sugar and 1/2 tsp fine sea salt flakes in a bowl. Add butter and toss to completely coat. Rub the butter in with your finger tips to coarse crumbs (leave some large pieces of butter to help create the flaky crust).
• 2.
  Combine vinegar, 1/3 cup (80ml) chilled water and 4 ice cubes in a jug. Make a well in the centre of flour mixture, then add vinegar water in 2 batches, and gently fold into flour mixture until you have a rough dough. Divide pastry into 2 pieces and shape each into a disc, then enclose in plastic wrap. Chill for at least 1 hour or up to 2 days.
• 3.
  Meanwhile, for the filling, toss rhubarb, strawberry, apple, 1 cup (220g) caster sugar, orange zest, vanilla and half of the cornflour in a bowl. Set aside at room temperature while the pastry rests.
• 4.
  Roll out 1 portion of pastry on a lightly floured work surface to a 3mm-thick circle and use to line the base and side of a 24cm pie dish (enamel is best here). Chill while you roll out the second piece of pastry. Roll out the second portion of pastry on a lightly floured work surface to 3mm thick circle. Cut out a neat circle that fits the top circumference of the pie dish (this will depend on the taper). Cut neat slits into the pastry to allow some air to escape, or create a design (we use a ravioli cutter to cut some slits in the pastry in a lattice-style design). Place on a tray lined with baking paper and chill until needed.
• 5.
  Combine remaining 1/2 cup (110g) caster sugar with sour cream and egg yolk and remaining cornflour. Combine with rhubarb mixture. Remove pie dish from fridge and add filling to the pie dish, then add pastry top. Press the pastry edges together to seal, then brush with egg wash and scatter with demerara sugar. Place on a baking tray. Chill while the oven preheats.
• 6.
  Preheat oven to 200°C. Bake pie for 35 minutes or until pastry begins to turn golden. Reduce to 180°C and bake for a further 1 hour or until deep golden. Rest for at least 1 hour before serving. Drizzle with thickened cream, to serve.