Preheat oven to 390° Fahrenheit/ 200° Celsius and prep a baking sheet with parchment paper.
Separate the egg whites from the yolks, placing the whites in a large bowl and the yolks in a smaller bowl. Add a pinch of salt to the egg whites and beat until almost stiff.
5 eggs, 1 pinch salt
Add about ¾ of the sugar and continue beating until stiff.
100 grams sugar
Beat the egg yolks with the remaining sugar and lemon zest until creamy.
100 grams sugar, 1 lemon
Mix together the flour, cornstarch and baking powder and add to the egg whites along with the egg yolk-sugar mixture, folding it carefully into the egg whites.
80 grams all-purpose flour, 30 grams cornstarch, 2 grams baking powder
Spread the batter onto the parchment-lined baking sheet and bake for 10 minutes or until golden yellow. Sprinkle sugar onto a kitchen towel and flip the warm sponge cake onto the sugar-sprinkled kitchen towel, leaving the parchment paper on top. Let cool completely
Wash the strawberries and finely dice ¾, pureeing the remaining ¼.
350 grams strawberries
Add together heavy whipping cream, sugar and vanilla and whip the cream until almost stiff. Add the puree and mix until completely stiff.
400 milliliters heavy whipping cream, 50 grams powdered sugar, 1 teaspoon pure vanilla extract
Fold in the diced berries and move to the fridge to stay cool. If the cake is cooled, carefully remove the parchment paper.
Heat the jam in 20 second increments in the microwave until warm and more workable, then brush onto the cake. Allow to cool.
150 grams strawberry jam
Spread the strawberry whipped cream onto the jam layer, leaving some room at the top edge, so that the mixture will not squeeze out when rolling the cake.
Using the kitchen towel, carefully roll the sponge cake (the long side should face your body and you'll roll away from you), applying even, light pressure.
The cake can now be garnished with more whipped cream on the outside and more fresh berries or you can dust it with powdered sugar like I did.
powdered sugar