Clean, wash and cut the rhubarb into pieces. Put rhubarb and 125 g sugar in a pot and let the juice stand. Add 5 tablespoons of water and vanilla pod and bring to the boil. Simmer on low heat for 3-4 minutes. Stir the starch in a little cold water until smooth and bind the rhubarb with it, bring to the boil again.
Let the rhubarb cool down. Mix curd and buttermilk. Stir in 30 g sugar, vanillin sugar and lemon peel. Arrange buttermilk-curd mousse with the rhubarb on plates. Serve decorated with lemon balm
Waiting time approx. 1 hour