Preheat oven for the floor (electric oven: 175 °C/circulating air: 150 °C/gas: see manufacturer). Grease the bottom of a springform pan (20 cm Ø). Whisk 3 whole eggs, 75 g sugar and 1 pinch of salt with the whisk of the mixer for approx. 5 minutes until thick and creamy. Mix flour, 25 g starch and baking powder, sieve over the egg mixture and fold in. Fill the sponge mixture into the mould, smooth it down and bake in a hot oven for 20-25 minutes.
For the cream, soak gelatine in cold water. Cut the vanilla pod lengthwise and scrape out the pulp. Boil up milk, 75 g sugar, vanilla pulp and vanilla pod. Mix 4 egg yolks, 75 g sugar and 30 g starch. Remove milk from the stove. Pour the egg yolk and starch mixture gradually into the hot milk, stirring continuously. Place back on the stove, heat up again and simmer gently for about 1 minute. Remove from the heat and allow to cool for approx. 10 minutes while stirring occasionally. Squeeze the gelatine and dissolve in the cream. Place the foil directly on the surface of the cream and let it cool down (do not put it in the refrigerator).
Remove the sponge cake from the oven, remove from the edge of the mould and allow to cool. Wash and clean 200 g strawberries and puree with lemon juice and icing sugar. Put them in a cold place.
Whip the cream until stiff, stir the cream until smooth. Fold in the cream. Cut the sponge cake base twice horizontally. Place a cake ring around the lower cake base. First 1⁄3 strawberry puree, then 1⁄4 spread the cream on the cake base. Place the middle cake base on top, spread 1⁄3 puree and 1⁄4 cream again. Place the top cake layer on top and spread the same. Chill the cake for about 1 hour, then carefully remove from the ring. Stir the rest of the cream until smooth again and spread it on the edge of the cake. Chill the cake for about 2 hours.
Wash 300 g strawberries, clean and cut into thin slices. First decorate the lower edge all around with strawberry slices. Place the remaining strawberry slices on the surface of the cake in a circle from outside to inside. Refrigerate the cake again for about 1 hour. Grate the chocolate or chop it very finely. Sprinkle the cake with chocolate before serving.