Sift flour and cocoa into a bowl. Add in sugar, salt, baking soda, and vanilla sugar, and mix well.
Add vinegar, water, and oil to the dry ingredients. Mix with a hand whisk.
If you use a silicone mold, pour the dough directly, otherwise, grease it with oil.
Put it in an oven heated to 150-160 °C and bake for 60-70 minutes. Check with a toothpick, if it comes out dry, it is ready.
Be sure to cool the cake in the form and then take it out.Note that if you use a different shape, with a larger diameter, the baking time will be reduced.Bon Appetit!