Separate the eggs, beat 4 egg whites and 1 tablespoon of water until stiff, add 75 g of sugar. Stir in egg yolks one after the other. Mix flour, baking powder and cocoa, sieve over the egg mixture and fold in
Line a baking tray (approx. 32 x 39 cm) with baking paper. Spread the mixture evenly on top. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Turn onto a tea towel sprinkled with sugar and carefully remove the baking paper. Roll up with the tea towel from a narrow side, allow to cool
Soak the gelatine. Drain the mandarins, collect the juice and put it in a pot. Add orange juice and 80 g sugar, heat up. Squeeze the gelatine and dissolve in it. Add the orange peel, chill until the mixture begins to gel
Beat 1 egg white and 40 g sugar, fold into the mixture. Whip 300 g whipped cream until stiff, fold into the mixture
Unroll the sponge cake plate again. Spread the cream on top, leaving an approx. 1 cm wide edge free. Place approx. 3/4 of the mandarin pieces next to each other on top. Roll up the sponge cake firmly and chill for 2-3 hours.
Shortly before serving, whip 200 g of cream until stiff, fill into a piping bag with star-shaped spout. Dust the roll with icing sugar, decorate with cream, chopped pistachios and remaining mandarins
waiting time approx. 3 hours