Set a kettle of water to boil. This will be used to create a water bath for the cheesecake.
Beat the cream cheese, sugar, and flour together on medium speed until just smooth — approximately one minute. Be sure to scrape the bottom and sides of the bowl.
Add the vanilla, lemon zest, lemon juice, and salt, and then beat on low speed until just combined.
Add the eggs one at a time, and mix on low speed until completely incorporated.
Mix in the sour cream. Do not over-mix.
When your oven has cooled to 325°F, pour the batter on top of the graham cracker crust.
Place the springform pan full of cheesecake batter into a large roasting pan.
Place in the lower middle rack of the oven.
Pour the boiling water into the large roasting pan. It should come about one inch up the side of the springform pan. (This is why it is important to use heavy duty aluminum foil and wrap twice to prevent any leaks in the water bath.)
Bake until the cheesecake is firm. (1 ½ hour to an hour and 45 minutes.)
Remove the roasting pan from the oven. Cool the cheesecake in the water bath for about 45 minutes.
Remove the springform pan from the water bath. Discard the aluminum foil.
Run a knife around the edge of the cake to prevent sticking.
Refrigerate cheesecake covered in plastic wrap 4 hours or overnight.