Clean, wash and cut the rhubarb into pieces. Bring apple juice, 250 ml water, vanillin sugar and rhubarb to the boil. Simmer over low heat for 10-12 minutes until the rhubarb crumbles.
Season to taste with sweetener. Stir starch and 3 tablespoons of water until smooth. Bring the soup to the boil, stir in the starch and bring to the boil again while stirring. Simmer at low heat for about 1 minute.
Select the raspberries and add them to the soup. Beat the egg whites with the whisks of the hand mixer in a tall beaker until stiff. Let sugar trickle in. Beat until the sugar has dissolved and the egg white becomes shiny.
Bring 1 litre of water to the boil in a wide saucepan. Switch down to low heat. Use 2 teaspoons to cut off small egg whites, add to the water, cover and let simmer on low heat for 6-8 minutes.
Pour the soup into deep plates and serve with egg snow dumplings and mint to taste.