Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a mixing bowl, combine flour, sugar, and salt. Add the cold vegan butter and mix until the mixture resembles coarse crumbs.
Gradually add ice water, one tablespoon at a time, until the dough comes together. Form the dough into a disk, wrap in plastic, and refrigerate for 30 minutes.
In another bowl, mix the berries, sugar, cornstarch, and lemon juice. Set aside.
Roll out the dough on a floured surface into a circle about 12 inches in diameter. Transfer to the prepared baking sheet.
Place the berry mixture in the center of the dough, leaving a 2-inch border. Fold the edges of the dough over the berries, pleating as you go.
Bake for 40 minutes, or until the crust is golden and the filling is bubbly. Let cool before serving.