In a mixing bowl, beat egg white and 1 tsp vinegar. Add white sugar batch by batch. Beat the eggs until soft peak and white.
Add the egg yolks into the beaten white eggs. With hand whisk, mix them slowly with clockwise motion.
Add the sifted flour and baking powder into egg mixture. Mix them slowly with clockwise motion.
Add the rest ingredients: oil, milk and vanilla essence. Mix them well.
Prepare your baking tray/muffin tin/bowl/bamboo steamer. Use paper in the bottom of tray (optional).
Prepare the steamer. Pour the batter into the bowl/muffin tin.
Steam the cake for 15-20 minutes according to your baking quantity. (If baking in muffin tin, it takes 10-12 minutes)
Transfer it out and let it cool down before slicing it.
The cake is spongy and soft.
