Cut the rhubarb into approx. 1 x 1 cm cubes, simmer together with apple-currant syrup and sugar for approx. 3 minutes. Then remove from heat and let cool.
For the brittle, boil down the sugar, butter and juice. Mix in the dry ingredients and spread the mixture flat on a baking sheet. Bake in the preheated oven at 180 °C convection oven for about 5 minutes.
Arrange the ice cream balls on a plate, spread the rhubarb on top and garnish with the brittle.