Leave out the eggs at room temperature. Preheat the oven to 355°F/180°C. Line a pan with baking paper.
Combine and shift the flour and matcha several times.
Put eggs and sugar in a bowl and put on a bain-marie at about 140°F/60°C. Whisk with an electric mixer at high speed.
Check the temperature of the egg mixture and when it's 97°F/36°C (it should feel a little warm to the touch), remove from the bain-marie and continue to whisk.
After the mixture is fluffy (about 5 minutes after the bain-marie) reduce the speed and whisk slowly for about 3 minutes.
Whisk until the batter looks like the photo. It looks shinier than when whisked at high speed. In this photo you might not see much difference, though.
Change to a whisk. Add 1 tablespoon of water and whisk gently (by adding water, the flour will mix in easily).
Add the prepared flour in one go and whisk about 40 times until shiny and thick.
Pour in the batter from above into the pan and flatten the surface with a dough scraper.
I omit spraying water on the surface because it doesn't make a lot of difference.
Bake in oven at 356°F/180°C for 12 minutes.
After baking, remove from the oven. Drop the pan on the cooling rack from 20-cm high to prevent shrinking.
Peel off the baking paper, wrap the sponge with cling film and lay on a cooling rack. Put the sponge and cooling rack into a large plastic bag and cool down completely.
Meanwhile, make the adzuki cream. Mix the tsubu-an, 50 ml of fresh cream and 1 tablespoon of milk until smooth.
Whisk the rest of the cream in another bowl until soft peaks form.
Add Step 14 into the soft-whipped cream and whisk until slightly stiff. Check your work as you go.
After the sponge has cooled down, slice off the edge at the far end diagonally to let the edges seal together nicely.
Spread the cream on the baked side of the sponge. Put more cream towards your end and less cream towards the far end.
Roll up the sponge and place the rolled sponge with the joint under. Wrap the Swiss roll with cling film and chill in the fridge for at least one hour.
After chilling, slice the Swiss roll with a warmed knife. Every time you slice, clean the blade to make eat cut nice and clean.
Moist Fluffy Plain Swiss Roll (Recipe ID: 1027626);
Chocolate version (Recipe ID: 1028702)
Cookpad user "Hina & Yume" made this Swiss roll with strawberries in the centre.
Story Behind this Recipe
This is my first green tea cake recipe.
When you mix the adzuki beans, the fresh cream will look runny at first, but don't worry. If you continue to whisk, the cream will whip quite nicely. When you peel off the cling film from the cooled sponge, it might damage the sponge surface but the cream will be on top, so don't worry.