Break the eggs, separate the whites from the yolks. Beat the whites to snow, add 1 cup sugar, 1 vanilla and continue stirring.
Then, beat the yolks and begin to pour them into the whites in a thin trickle. Once everything is mixed well, add 1 cup flour - a little at a time.
Note - I didn't use any kind of raising agent! Bake in a 302°F (150 °C) oven (not preheated) with the fan on until your toothpick comes out dry when you poke it.
While the sponge cake is cooling, prepare the water, sugar and grate the lemon in it. It gives it a spectacular taste. Leave it to boil until the syrup thickens visibly. For those who love a stronger aroma, you can add a stick of cinnamon and 1-2 cloves.
Pour the boiling syrup over the cooled cake, it will absorb it right away. You can use even more of it. Personally, I like to have it drip from my fork.