Prepare the cake tins: Grease two 7 inches (20cm) round cake tins and line the bottoms with parchment paper.
Sift your dry ingredients: Sift the flour, cornflour, baking powder, and sugar into a large bowl.
Add the oil to the dry ingredients: Add the oil to the dry ingredients and beat with a whisk or electric mixer on low speed. Little clumps will form as you beat, this is okay, it's just the oil coating the dry ingredients.
Pour in the milk and add vanilla extract. Beat on medium speed for one minute until the batter is smooth and free of lumps.
Pour the vinegar into a small bowl and add in the baking soda. The baking soda starts to fizz and react as soon as it is mixed with the vinegar.
Combine this immediately into your cake batter and beat for about 10 seconds.
Transfer to your lined cake tins. Transfer the batter to your lined cake tins. The cakes should be put into the oven soon after beating in the vinegar and baking soda.
Bake in the oven at 320°F/160°C for about 25-30 minutes or until a skewer or knife inserted in the center of the cake emerges clean.
Let it cool in the tins for 10 minutes before transferring to a wire rack to cool completely.