Knead flour, icing sugar, salt, butter in flakes and the egg with your hands to a smooth dough. Wrap dough in foil and chill for about 30 minutes.
Cut the vanilla pod lengthwise and scrape out the pulp with the back of a knife. Bring 200 g cream, 75 g sugar, vanilla pulp and pod to the boil and simmer for about 3 minutes. Remove the cream from the heat and add 400 g cream, let it cool down for about 30 minutes.
Roll out the dough rectangularly (approx. 13 x 37 cm) on a floured work surface. Grease the tart mould with lift-off base (approx. 11 x 35 cm) and line with dough. Fold the protruding edges inwards and press firmly.
Place baking paper on the dough. Add the dried peas and pre-bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 10 minutes. Remove baking paper and dry peas, bake the base for another 5-10 minutes at the same temperature until golden brown.
Remove the tart base from the oven and let it cool down on a cake rack.
Soak gelatine in cold water. Squeeze the gelatine, dissolve in the warm cream, chill for approx. 30 minutes until it starts to gel. Pour onto the tart base and chill for at least 3 hours.
Wash and clean the rhubarb and cut into diagonal pieces. Bring cranberry juice, wine and 50 g sugar to the boil. Add rhubarb and simmer for about 1 minute. Remove the rhubarb. Mix starch and 2 tablespoons of water and thicken the rhubarb stock with it.
Simmer for about 1 minute, then let it cool down while stirring occasionally, add rhubarb and let it cool down.
Lift the tart out of the mould. Spread some rhubarb compote on the tart and dust with icing sugar. Serve the rest of the compote with the tart.