Vanilla Sponge Cake "without baking powder"

 

INGREDIENTS LIST:
4 egg yolks (18 - 20 gram/ yolk)
20 gram caster/ superfine sugar
40 ml milk
30 ml vegetable oil
1/2 tsp vanilla extract
50 gram all purpose flour
50 gram corn starch
4 egg white (30 - 35 gram/ egg white)
a pinch salt
1 tsp white vinegar
70 gram caster sugar