Preheat the oven to 350°F (180°C) on conventional bake. Grease a round cake pan with a little oil or butter, then lightly dust it with 1–2 tablespoons of flour.

Separate the eggs. In a clean bowl, beat the egg whites with a pinch of salt until stiff peaks form. In another bowl, whisk the egg yolks, water, and sugar together until creamy and frothy.

In a separate bowl, whisk together the flours and baking powder. Sift the flour mixture into the creamy egg yolk–sugar mixture and gently fold it in. Then carefully fold in the beaten egg whites.

Pour the batter into the prepared cake pan and smooth the top. Bake for about 20 minutes, then let the cake cool completely before removing it from the pan.

Wash the strawberries, remove the green stems, and cut them in halves or quarters. Arrange the strawberries on top of the cooled sponge cake.

In a small bowl, mix the cornstarch, sugar, and 1/3 cup (about 3 fl oz/80 ml) of the water to form a smooth, lump-free paste. Bring the remaining water to a boil in a small saucepan.

Once the water is boiling, stir in the cornstarch mixture. Reduce the heat slightly and continue stirring until the liquid thickens noticeably.

Use a tablespoon to evenly spread the glaze over the strawberries on the cake. Chill in the refrigerator for about 1 hour to allow the glaze to set, then serve.