To the mixing bowl, sift all-purpose flour, powdered sugar, and cornstarch. Add vanilla sugar, ground walnuts, and sea salt. Mix all together. Then add soft vegan butter. Knead everything using a hand mixer or your hands to knead the dough until it forms.
Roll the dough into a 16 cm (6,3 in) long roll and wrap it in a plastic wrapper. Put the dough into the fridge for at least 3 hours (preferably overnight) to let the dough firm.
After chilling the dough, take it off the fridge**. Preheat the oven to 180°C and line the baking tray with parchment paper.
Cut the roll with a knife into 16 slices (1 slice should be about 1 cm/0,4 inch thick).
Then divide each into 4 even pieces (the edges probably into 2-3 pieces). Roll each slice into a small roll (about 6,5 cm/2,6 inches long) and carefully bend both ends to form a crescent cookie shape. If the dough is breaking apart, try to knead the dough a few times in your hand to warm it a little.
Carefully transfer the cookies onto a baking tray with parchment paper. Bake in preheated oven for about 7-12 minutes until the ends start to get slightly golden. Baking time depends on how thick your cookies are, so make sure to keep your eyes on them.
Meanwhile, the cookies are baking, mix powdered sugar and vanilla sugar (or ground vanilla) in a deep plate.
After cookies are baked, let cool for about 1-2 minutes. Then, when they are still warm, transfer to the plate with vanilla sugar mix and fully coat them in it.
Let the cookies cool completely and enjoy! ***