In a deep container, beat the eggs with sugar until fluffy. For convenience, use an electric mixer.
Add sour cream and flour to the egg mixture. Mix everything thoroughly.
Add lemon zest to the dough and stir.
Grease a baking pan with butter and pour the biscuit dough into it.
Bake the sponge cake in the oven at 180 ℃ for 30 minutes. Leave the finished sponge cake in the pan for another 5-10 minutes. Then cut the sponge cake into portions and place on serving plates. Decorate the sponge cake with orange slices, berries and powdered sugar. Enjoy!