For the rhubarb compote, clean, wash and chop the rhubarb. Caramelise 100 g sugar in a pot. Add rhubarb and 100 ml hot water. Simmer open over a high heat for 6-8 minutes until the rhubarb is soft and largely decomposed. Remove from the heat and let it cool down
Separate 5 eggs for the meringue. Beat the egg whites until very stiff, gradually adding salt and 200 g sugar. For the sponge cake, beat the egg yolks and 2 eggs with 50 g sugar until thick and creamy. Sift the flour over it and fold in carefully. Fill both masses into piping bags with very large perforated spout. Line a baking tray (34 x 40 cm) with baking paper
Spray 6 strips of meringue lengthwise onto the baking tray, leaving spaces of approx. 2 cm between each strip. Now squirt the sponge mixture into 4 of the spaces. Leave the middle space free. Bake in the preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: see manufacturer) for 25-30 minutes until the pastry is lightly browned. Let them cool down on a cake rack. Carefully turn meringue biscuit plates over onto a second piece of baking paper, carefully peel off the baking paper. Fold the plates back with the help of the baking paper
Soak gelatine in cold water. Weigh 350 g rhubarb compote, mix with sour cream and syrup. Squeeze the gelatine, dissolve carefully. Stir a little cream into the gelatine, then stir everything into the remaining cream. Put it in a cold place. Whip cream until stiff. When the cream begins to gel, carefully fold in the cream. Spread the cream on a strip and smooth it down. Carefully place the second strip on top. Whip excess baking paper over the slices. Chill for about 2 hours. Dust with icing sugar to serve. Add the rest of the compote
waiting time approx. 2 1/2 hours