Wash and stone the cherries. Set 3 cherries aside. Wash lemon, grate dry, grate some peel and squeeze.
Bring cherries, a good 1/4 l water, lemon juice and zest, 1 packet of vanilla sugar and 80 g sugar to the boil in a saucepan. Simmer at medium heat for about 15 minutes.
Stir pudding powder and 3-4 tablespoons of water until smooth. Stir into the cherries, bring to the boil again and simmer for 1-2 minutes. Season with sugar if necessary. Let the groats cool down. Then fill into glasses and let them cool down.
Whip the cream with the whisk of the hand mixer until semi-stiff. Stir yoghurt and 1 sachet of vanilla sugar until smooth. Fold in the cream. Season to taste with sugar and spread on the groats. Halve the remaining cherries.
Decorate the groats with pistachios and the cherry halves.