Knead flour, egg, oil, salt and 1/8 litre of lukewarm water with the dough hooks of the hand mixer to a smooth dough. Knead with your hands on a floured work surface until it is smooth and silky shiny.
Cover and leave to rest for about 2 hours at room temperature. Meanwhile, clean and wash the gooseberries for the filling. Bring 1/2 litre water and sugar to the boil. Cook the gooseberries in the hot sugar solution for 5-8 minutes, drain and allow to cool.
Melt the fat in a pot and let it cool down. Dust a large kitchen towel with flour and roll out the dough into a rectangle with a paper-thin roll of dough (you must be able to see the structure of the towel).
Spread the pastry plate with half of the liquid butter and sprinkle with almonds and vanillin sugar. Spread the drained gooseberries evenly on the strudel, leaving a 3 cm wide rim all around.
Roll up the strudel from the broad side with the help of the kitchen towel and place it on a baking tray lined with baking paper. Wrap the ends and brush the strudel with the remaining liquid fat.
Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for 30-40 minutes. Dust the strudel with icing sugar. Results in about 18 pieces.