Soak the hazelnuts overnight in cold water. Drain the hazelnuts, rinse with cold water, puree in a blender along with 500 ml of fresh water and salt. Pour the hazelnut mixture through a cheesecloth, squeeze gently in the cloth. The residue from the hazelnuts can be kept, left to dry out completely and used to make crackers. See recipe: Nut crackers. Pour the hazelnut drink into a clean bottle that has been rinsed with hot water.