Beat the egg whites until foamy, then add sugar. Keep beating until still peak formed. 

Heat the oil in microwave for 90 seconds on high, or you can heat the oil on the stove for one minute. Add in flour and salt, mix well. Add in egg yolks and milk, mix until smooth. 

Add meringue bit by bit into the batter, fold it gently. 

Pour the batter into lined baking tin, bang the cake tin for few times to release the air bubbles. Put the cake tin in a larger baking sheet, then pour hot water into it to make a water bath. Pop into preheated oven at 150C, bake for about an hour or until fully cooked.

Once it cooked, bang the cake tin few times , this can prevent the cake from shrinking. Let it cool completely then slice it. Enjoy!