Flour, for dusting
400g Edmonds short sweet pastry
6 cups boysenberries
3⁄4 cup sugar, plus 1 tbsp. for sprinkling
3 tbsp. cornstarch
1 tsp. ground cinnamon
1 tsp. grated lemon zest
1⁄4 tsp. kosher salt
1 egg, lightly beaten with 1 tbsp. water
On a lightly floured surface, roll ¾ of the pastry into a 30cm round. Fit into a 22 pie plate. Trim edges, leaving 2cm dough overhanging edge of plate; chill 30 minutes.
Heat oven to 200°C.
Combine 1 cup berries, 3⁄4 cup sugar, cornstarch, cinnamon, zest, and salt in a bowl; mash and mix together. Stir in remaining berries; pour over dough. Roll remaining pastry flat and cut into 2cm strips and place over top of pie. Pinch top and bottom edges together and fold under; using the tines of a fork, press edges to seal. Brush with egg mixture; sprinkle with 1 tbsp. sugar. Bake until crust is golden brown and filling is bubbling, about 1 hour. Let cool completely before serving.