Preheat oven to 350 degrees Fahrenheit. Lightly grease a springform pan with removable sides.

Prepare the crust: In a bowl, mix graham cracker crumbs and sugar. Add margarine and stir until crumbs look like wet sand. Press gently onto the bottom of the prepared pan and about half an inch up the sides. Set aside.

Prepare the filling: In an electric mixer fitted with the whisk attachment, beat egg whites until stiff peaks form. Gently transfer to a separate bowl and set aside to use in step 5. (No need to wash the mixer bowl.)

Remove the whisk attachment and fit the mixer with the paddle attachment. Beat egg yolks, sour cream, cream cheese, sugar, vanilla extract, and lemon juice until creamy.

With a spatula, fold the whipped egg whites into the cheese mixture. Pour into the prepared crust.

Create a water bath: Place the springform pan on a baking sheet lined with a double layer of heavy-duty aluminum foil. Bring edges of foil up and mold them around the outer sides of the pan to form a watertight seal.

Place the springform pan inside a large roasting pan. Carefully pour boiling water into the roasting pan so it reaches halfway up the sides of the springform pan. Be careful not to get any water in the cheesecake.

Bake for one hour.

Turn off the oven. Leave cheesecake inside for 20 more minutes to set (leave oven door closed).

Remove from oven. Cool completely and chill before serving. If you like, decorate with toppings of your choice.