Pour gelatin into the berry juice, mix and dissolve over low heat.
Mix sour cream, syrup, berries and gelatin.
Whisk the whites until they reach firm peaks, and gently mix with the mixture.
Berries can be taken and freshly frozen. They do not need to be defrosted and added to the mixture after all the other ingredients are mixed until a homogeneous mass is obtained. Because the mass hardens immediately upon contact with the gelatin mass.
Distribute the mass into glasses and refrigerate for at least 2 hours until solidified. Garnish with berries, mint and serve.