Move an oven rack to the center position.
Preheat the oven to 300° F. (Yes, 300 F.!)
Generously butter the inside of a 10-inch springform pan.
Wrap a double layer of heavy-duty aluminum foil tightly around the outside of the springform pan, and around the bottom and sides, crimping and pleating the foil to conform to the pan.
In a large bowl, whisk by hand the eggs and sour cream until well-blended. Set aside.
With a mixer on medium-high speed, beat the cream cheese with the butter until smooth and creamy. On low speed add in the egg mixture, gradually increase the speed to medium and mix it well.
On medium high speed, beat in the sugar, cornstarch, vanilla extract, lemon juice and lemon zest. Beat thoroughly until it is all mixed,, about 2 minutes.
Make a water bath by placing the springform pan into another larger pan that is filled with very hot tap water about one-quarter full. Wait a few minutes to make sure no water is leaking into the springform pan. If it does leak, then add more aluminum foil on the bottom and around the sides of the springform pan.
Pour the batter into the prepared springform pan.
Bake the cheesecake at 300° F. in the water bath for 2 hours and 15 minutes, or until it is very lightly browned, and a cake tester inserted in the center comes out clean.
Remove the springform pan from the water bath. Peel off the aluminum foil.
Place the pan on a wire rack to cool at room temperature for 4 hours.
Cover it and refrigerate it overnight or at least 4 hours before serving.