Step 1

Blend egg yolks, yogurt, lemon juice and vanilla extract to smooth.

Step 2

Sieve in flour and corn flour, followed by lemon zest and fold well to smooth with a spatula.

Step 3

Whisk egg whites and lemon juice till foamy and add sugar in 3 batches to soft peak forms.

Step 4

Line a 6 inch (non stick baking paper) with removable base round cake pan, and pour in batter. Wrap the cake pan with aluminium foil to prevent batter seeped through the pan while baking. *can use 7 inch cake pan but the cake will be lower after baked**

Step 5

Steam bake cake in preheated oven at 120 deg C for 75 minutes, then at 150 deg C for another  5-10 minutes till the top of the cake is slightly browned.

Step 6

Remove the cake from the oven and drop the pan on table top to release hot air. Remove cake from pan while it is still hot and leave to cool on wire rack.

Step 7

Best to chill cake in refrigerator for a few hours before serving. Slice cake with a hot knife.