For the Cake batter

1. Preheat the oven to 160℃ (325 ℉).
2. Combine egg yolks and caster sugar in a large mixing bowl, whisk at medium speed using a hand-held mixer until the mixture thickens and turns pale in colour. This should take around 5 minutes.
3. Add milk, oil and vanilla extract into the mixture and whisk together until well blended.
4. Place a sieve on top of the mixing bowl. Sift in the flour, baking powder and salt.
5. Whisk the mixture at medium speed until the batter is almost fully combined. 
6.  Finish mixing the mixture by hand using a silicone spatula. Set aside.

Prepare the meringue

1. Pour the egg whites and vinegar into a clean and dry mixing bowl. Use a hand-held mixer with a whisk attachment. Whisk them at medium speed until foamy.
2. Add the caster sugar into the egg whites in three portions. Allow around between 30 seconds to 1 minute in between adding each portion to allow the sugar to dissolve.
3. After adding all the sugar, turn the mixer to medium high speed and continue to whisk the meringue until it reaches its stiff peak form. You can check it by drawing the meringue out, using the whisk. If a firm peak is formed, it’s done.

Fold the meringue into the cake batter

1. Using a spatula, scoop a small amount of meringue and add it to the cake batter. Mix it in, using a manual whisk, this helps to loosen the thick texture for easier mixing.
2. Scoop ⅓ of the meringue into the batter and continue to mix it in using the manual whisk until you can’t see any white patches. Keep your movements very gentle and always mix in the same direction.
3. Continue to scoop in the remaining portions of meringue until everything is well mixed.

Bake and cool the cake

1. Prepare an 8-inch tube pan. DO NOT grease it.
2. Pour the cake batter into the pan at the same spot.
3. Hold the pan a few centimetres off the work surface and then drop it to get rid of any big air pockets trapped in the batter.
4. Run a skewer in the batter in a swirling motion, again to remove any remaining air pockets.
5. Shake the pan a few times to evenly distribute the batter if needed.
6. Place the pan on the lowest rack in the preheated oven and bake around 40 to 45 minutes. DO NOT attempt to open the oven door while the cake is baking.
7. To check if the cake is done, no sooner that 35 minutes into the baking time, insert a skewer in the centre of the cake and if it comes out clean, it means the cake is done.
8. Take the cake pan out from the oven and immediately invert the pan onto a wire rack. Allow it to cool down completely.

Un-mould the cake

1. Prepare a serving plate.
2. Run an icing palette knife along the edges and the funnel of the pan.
3. Push the bottom of the pan to release the cake.
4. Run the palette knife again along the bottom of the pan.
5. Turn the cake upside down on top of the serving plate, the cake should slide free from the pan.
6. Serve it on its own with a cup of tea / coffee or dust it with icing sugar for garnish. Enjoy!