I've come across this step-by-step sponge roll with strawberries recipe, a sweet common in Japan, at least judging from the photos I see around the internet. I decided to give it a try!
4 egg yolk
1/4 cup of milk
1/2 cup of flour
4 egg whites
1/2 cup of fresh cream
1/4 cup of corn oil
sugar to taste
a few drops of vinegar
Put egg yolk into a bowl. Add oil, milk, sugar (I used 3 spoons of powdered sugar) into the bowl and mix until water and oil blend together (I used a blender to mix them very well, until the mixture started to take on pale yellow color and bubbles appeared). Next sift in flour (I used self-rising cake flour) (for czech readers: hladká mouka a kypřící prášek) and mix until there are no clumps.
In to another bowl, add egg white with vinegar and beat until stiff with peaks. Put one third of the beaten egg whites into the batter and mix evently. Put the rest of the beaten egg whites, fold gently.
Pour the batter into a parchment lined pan and spread it evenly across the pan. Gently knock the pan down a few times to get rid of bubbles in the batter. Put in 180 C preheated oven and bake for 15 minutes. Take the cake out and let it cool.
In the meanwhile, beat the cream and wash the strawberries. Then take the cooled cake and flip it over on the parchment paper (I flipped it into another paper I put on top, rather). Spread the cream, put the strawberries on one end. Roll the cake (it was surprisingly easy to roll it!), wrap it with the parchment paper, and put it into the fridge to cool for half an hour.
Here goes the result! It was delicious, I'll be making it regularly for sure.