Make sure the cream cheese, the sour cream and the eggs are at room temperature. Read NOTES below.
Whisk the dry ingredients together in a bowl (the sugar and the cornstarch). Keep aside.
Next, add the room temperature cream cheese in a big mixing bowl. Break the slabs with the help of the lowest setting in your hand mixer. 20 seconds approx.
Now, add half of the sugar cornstarch mixture, beat with the help of your hand mixer kept at the lowest setting until just incorporated. It should take you 30-40 seconds approx.
Add the rest of the sugar mixture and mix until just incorporated using the same speed. Scrape down the sides of the bowl with the help of a rubber spatula.
Now, add the sour cream and the vanilla extract and beat together until just incorporated, 30-40 seconds approx. Keep the speed of your hand mixer at the lowest setting always.
Whisk the room temperature eggs in a separate bowl with the help of a whisk. This step helps to easily and quickly incorporate the eggs into the batter and prevents from over mixing the batter.
Pour half of the whisked eggs into the batter and just incorporate with the help of your hand mixer kept at the lowest setting. Repeat this step once again for the rest of the whisked egg. This is known as mixing one egg at a time. This is VERY IMPORTANT that you do not over beat or over mix the eggs at this stage.
Pour the cheesecake batter into the cheesecake pan. Even out the batter with the help of a rubber spatula.
Burst the air bubbles in the batter by tapping the cheesecake pan a number of times on the kitchen counter top. This helps the air bubbles to surface on the top of the filling and burst them. You can also gently stir the cheesecake filling with the help of a fork to pop the air bubbles. Now, the cheesecake is ready to be cooked.