Steamed Sponge Cake

Bolu Kukus (Indonesia) or we can call "Steamed Sponge Cake" 
this time I want to write in english, such as "Minna" request :), here it this...

Steamed Sponge Cake (Bolu Kukus)

Ingredients:

* 5 egg yolks

* 4 egg white

* 250 gram granulated sugar

* 300 gram flour

* ½ tsp baking soda

* 175 cc soda water (Sprite/7Up)

* ½ tsp vanilla

* 1 tsp coloring pasta (or any foodgrade coloring as you like)

Instructions:

• Cover approx. 20 tin cups used to steamed the cakes with parchment papers then put them into a steamer pot with boiling water.
• Mix egg yolks, egg white, baking soda, sugar and vanilla until they make a smooth batter then put in turns, ½ portion of the flour, ½ portion of the soda water until all of them are used, mix well. Take 5 Tbs of the batter and put it in a separate bowl. Pour in the coloring pasta and mix well.
• Pour the white batter into the tin almost to the top then pour in 1-2 tsp of the coloring batter on top. Do this until all the batter is used up, ± 20 tin cups.
• Close the steamer lid, let it steamed for ± 20 minutes with high temperature. Then use low temperature for another 5 minutes. The cake is ready to serve if it looks like the above picture.