In a microwavable mixing bowl, whisk milk and oil together until well combine and microwave for 20 seconds.
Sift cake flour and matcha powder into the bowl, roughly mix just until you can't see any dry flour, no need to mix until smooth yet.
Add in egg yolks and salt then whisk just until smooth. Mix in the motion of writing "Z" and "N" instead of a circular motion in order to prevent developing gluten. Cover and set it aside.
Preheat oven to 310°F (155°C)
In a dry and clean mixing bowl, add vinegar in egg white and then beat until the egg white is foaming.
Add in a third of the sugar before beating some more. Do this three times, beating at medium speed, until all the sugar is incorporated and you can form soft peaks with the egg whites. (see the pictures in the main post as a reference)
Scoop about one cup of egg white into the egg yolk batter and mix to combine before pouring the resulting mixture back into the rest of the egg white.
Mix with a spatula from bottom to top in the motion of writing "J" while turning the mixing bowl, so the mixture can be well combined. Don't stir in a circular motion or over mix, as that would cause the mixture to deflate.
Pour the mixture into a 6 inch cake pan, use a chopstick or skewer to run through the batter to remove larger air bubbles.