Mix 250 ml cold water and jelly powder in a small saucepan and let it swell for about 5 minutes. In the meantime wash the currants, drain well and pluck the berries from the panicles. Add sugar to the liquid and heat while stirring (but must not boil). Remove from the heat and stir in another 100 ml of cold water. Arrange the currants in four dessert glasses.
Pour the liquid evenly onto them. Put them in a cool place overnight. Whisk the sour cream and vanilla sugar with the whisk of the hand mixer. Serve the jelly with a blob of sour cream and, if desired, a currant pancake and crumbled amarettini.
Waiting time approx. 12 hours