Preheat the oven to 180℃ with steam. If you're oven doesn't have a steam function, pour some water into a heat resistant dish and place it in the oven while it preheats.
Mix all of the ingredients together in a bowl with a whisk. Feel free to sieve the dry ingredients if you'd prefer.
Pour the ◎ ingredients into the bowl and mix with the dry ingredients until smooth.
Next, add in the cider vinegar and mix the batter briskly. Then pour the batter into your cake tin and bake it for 25 minutes at 180℃. Since the baking powder and vinegar will react, the cake will expand as it bakes.
Once the cake has baked, allow it to cool inside the tin. Since the cake is fluffy and full of air bubbles, treat it gently.
Once cooled, gently remove it from the tin and wrap it in cling film. Then leave the cake to sit.
Lastly, decorate the cake however you like. I filled this cake with strawberry slices and topped it with strawberries, grapes, and persimmon.
Story Behind this Recipe
I really wanted my daughter who is allergic to eggs to be able to eat a decorative fluffy sponge cake. Egg-free cakes tend to be chewy and heavy rather than fluffy so I tried aiming for a cake that's fluffy but not dried out.
I added in cocoa to cover up the taste of the baking powder. If you're making a decorated one, though, with other ingredients topped on it, you could also try preparing it without the cocoa. When you add the vinegar at Step 5, the batter will begin to expand quite quickly so please mix it in and get the batter in the oven as quickly as possible.