For the frozen yogurt, whisk the yogurt with sugar and vanillin sugar.
Cover and freeze for approx. 2 hours, stirring well every 20 minutes to loosen the ice layer at the edge.
After 2 hours, blend the frozen yogurt with a hand mixer (stir sticks) until smooth.
Puree the strawberry-rhubarb jelly with a hand blender and divide among dessert glasses.
Arrange the frozen yogurt on top and sprinkle with pistachios.