Bring soy milk with salt and sugar to a boil in a pot. Stir in the pudding rice, bring to a boil again and let it simmer for about 30 minutes on rather low heat, stirring occasionally. Leave the finished rice pudding to cool.

Stir the cornstarch into some soy milk until smooth. Add with the quark to the rice pudding. Whip the aquafaba according to this recipe and gently fold it in. If desired, add the optional lemon zest.

Grease a large baking dish with some vegan butter. Add the rice pudding mixture and the sour cherries alternatively. Put some flakes of butter on top. Bake in the oven at 180 degrees for about 50 minutes.