Prepare the Jam: In a medium saucepan, combine raspberries, granulated sugar, water, and cornstarch. Cook over medium heat for 5 to 10 minutes, mashing the fruit until thickened. Remove from heat and cool.

Make the Pastry: In a large bowl, combine flour, vegan butter, and powdered sugar. Mix until resembling coarse crumbs. Gradually add cold water, mixing until a soft dough forms, about 5 minutes.

Roll Out the Dough: Roll the dough on a floured surface to about 5 mm thickness. Use a cutter to make circles for mini tart tins.

Assemble Tarts: Press each dough circle into greased tart tins and fill with 1 tablespoon of cooled jam mixture.

Bake: Bake in a preheated oven at 180°C (350°F) for about 20 minutes until golden brown.

Cool and Serve: Allow tarts to cool in tins for 10 minutes before transferring to a wire rack. Enjoy warm or at room temperature.