Preheat oven to 400° F (205° C). Line a half sheet rimmed baking tray with parchment.

In a medium bowl, combine strawberries with granulated sugar, cornflour, lemon juice, lemon zest, vanilla bean paste, and kosher salt. Set aside and allow the berries to macerate for 15 minutes, or until soft and syrupy.

Meanwhile, unroll the pastry on a silicone rolling mat. Use a knife to trace around a large dinner plate or pastry ring, cutting a disc approximately 9-10 inches in diameter.

Flip onto prepared tray.

Spoon the strawberry mixture into the middle of the pastry, allowing 1 – 1 1/2-inch border around the outer edge.

Fold the edges of the pastry inward to seal in the strawberry mixture.

With a pastry brush, brush the pastry with beaten egg.

Sprinkle the fruit and pastry with Demerara sugar.

Bake in preheated oven for 30 minutes, or until bubbly and golden brown.

Serve warm, accompanied by vanilla ice cream, custard, or whipped cream.

Store leftovers in an airtight container in the refrigerator for up to 3 days.