Preheat oven to 170 C
Mix in egg yolk, vanilla and salt together, blend well, no need to heat
Measure out ingredients, oil and milk can be in 1 bowl. Salt, egg yolk, and vanilla extract can be in 1 bowl
Make meringue-beat egg white and slowly add sugar in 3 stages. Beat until firm peak 
Add in egg yolk mixture and slowly beat till blend
Swift in flour and fold carefully, don’t break the egg whites!
Take some egg white flour mixture and add to oil and milk bowl, mix till it has ribbon state
Mix back into the egg white mixture and fold till blend
Pan it
Run a toothpick to cut out big bubbles, put in oven for 30 minutes