Preheat oven to 355˚F (180˚C) and grease an 8-inch (20cm) cake pan. (You can line it additionally with parchment paper for easier removal).
Sift the flour, cornstarch, baking powder, and baking soda into a large bowl. Add salt and sugar and whisk to combine.
Add the oil, sparkling water, vanilla extract, lemon zest, and vinegar. Stir until just combined. (Please do not overmix or the cake will get dense instead of fluffy. It’s okay if the dough looks a bit lumpy instead of super smooth).
Fill the dough into the prepared cake pan and bake for approx. 35 minutes, or until a toothpick inserted in the center comes out clean and the surface of the cake springs back when gently touched with your fingertips.
Remove from the oven, allow to cool in the pan for 15 minutes. Then, carefully, invert onto a wire rack to cool completely.
Add strawberries, powdered sugar and lemon juice to a blender and blend until smooth (or use an immersion blender).
Split and scrape the vanilla bean. Mix the non-dairy mascarpone, powdered sugar, and vanilla with a handheld mixer until creamy. Set aside.
In another bowl beat the non-dairy whipping cream until stiff. Then, carefully, fold in the creamy mascarpone.
Assembling the Cake
Cut the cake horizontally in three equal layers. Place one cake layer on a serving plate and, optionally, place a cake ring around.
Spread 1/3 of the strawberry layer over the cake. Then spread 1/4 of the vanilla cream over it. Top with the next cake layer, another 1/3 of the strawberry layer, followed by another 1/4 of vanilla cream. Also, repeat for the third layer.
Carefully, remove the cake ring, if using, and spread the remaining vanilla cream all over the cake and sides.
Place your cake for at least 1 hour in the fridge to set before decorating and serving.
Decorate your cake with sliced strawberries and sprinkle over grated vegan white chocolate.