For the pastry, mix flour with 80 g of sugar, baking powder and 1 tbsp of soy flour. Add cold margarine in chunks and knead into a smooth dough. Wrap in film and chill for 30 minutes.
For the filling, mix Silken Tofu with 150 g of sugar, starch, vanilla pulp, lemon zest and juice, rapeseed oil and 2 tbsp soy flour at high speed until smooth.
Preheat oven to 180 °C. Grease a large springform cake tin and line with the pastry, including 2/3 of the sides. Spread the filling into the pastry case and bake for 45-55 minutes.
For the meringue topping, beat the aquafaba with a hand mixer for 5-10 minutes. Slowly add the cream of tartar, icing sugar and vanilla extract.
Spread the meringue onto the filling for the final 20 minutes of baking time.
Let the cake cool and remove from the tin.