Separate the eggs for the sponge cake. Beat the egg yolks and 2 tablespoons of warm water until frothy. Add 60 g sugar and lemon zest and beat until the mixture is light and creamy. Beat the egg whites until stiff, add the remaining sugar. Pour the beaten egg whites onto the egg yolk mixture. Mix flour, starch and baking powder, sieve over it and carefully fold in with a dough spoon.
Line a baking tray with baking paper. Spread the dough into 6 squares of approx. 13x13 cm. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for 10-12 minutes. Remove from the baking tray immediately, fold over and let cool on a grid. For the filling, soak gelatine in cold water. Wash the nectarines and remove from the stone. Puree the fruit flesh in the lime juice. Add liqueur and vanillin sugar. Squeeze the gelatine, dissolve lukewarm and stir into the fruit puree. Chill the jelly until it begins to set. Whip cream and sugar until stiff, fold into the puree. Pour into a piping bag with a large perforated spout.
Add liqueur and vanillin sugar. Squeeze the gelatine, dissolve lukewarm and stir into the fruit puree. Chill the jelly until it begins to set. Whip cream and sugar until stiff, fold into the puree. Pour into a piping bag with a large perforated spout. Fill omelettes with it. Refrigerate again. Dust with icing sugar and serve decorated with nectarine slices