Start by preheating the oven to 350°F degrees (180°C) and prepare a baking pan. I will use an 8-inch baking ring. I used a piece of parchment paper and foil to cover one side of the ring. Try your best to attach the foil to the ring so that the cake batter doesn’t leak out. If you’re using a regular baking pan or a springform, just cover the bottom of the form with parchment paper.
In a small mixing bowl combine the sour cream with the vegetable oil and mix them well.
In a stand mixer bowl combine the eggs, salt and sugar. Beat the eggs using the medium-high speed for about 8 to 10 minutes or until they’re light and fluffy. Towards the end, add the vanilla extract and whisk for one more minute. You should get a thickened and fluffy egg mixture that has lightened in color.
Combine the flour, cornstarch, baking powder and sift in about half of the dry ingredients. Carefully mix it all together, using a spatula. Sift in the rest of the flour mixture and mix again. Add the sour cream mixture and mix all the ingredients together using a spatula. Mix the ingredients with gentle movements so that the cake batter doesn't deflate.
Pour the cake batter into the prepared baking ring. Spread the cake batter evenly, using a spatula. Bake 350°F degrees (180°C) for 45-50 minutes. Check the readiness of the cake with a skewer or toothpick. The skewer inserted into the cake should come out dry.
Let the cake cool in the baking ring for about 10 minute or so, then using a sharp knife, run the knife between the cake and the baking ring. Take the ring off, invert the cake and carefully take off the parchment paper from the bottom. Let the cake cool completely. Once it has cooled, cover it with plastic wrap and refrigerate for a minimum of 2-4 hours or overnight.
Using a cake leveler or a bread knife divide the chilled cake into three layers.