A couple of hours before you are ready to serve the cheesecake, make the meringue.
Using a stand mixer or hand mixer, whip the egg whites and cream of tartar on medium low until soft peaks form.
Add the sugar in a steady stream (not all at once) and whip the egg whites on medium high until stiff peaks form. Then, switch the mixer to high speed and whip about 45 seconds to 1 minute or until the egg whites are stiff and glossy (judge by the gloss and stiff peaks).
Remove the cheesecake from the refrigerator and spoon the egg whites onto the top of the cheesecake. Mound the whipped egg whites on top of the cheesecake. Then, using the back of a spoon, form small peaks/curls on top of the egg whites by gently pulling the top of the egg whites into peaks. Finally, seal the edges of the cheesecake with the egg whites.
Turn on and set the oven to 400 degrees. Place the cheesecake in the oven on the center rack for a few minutes or until golden brown. YOU MUST WATCH THE CHEESECAKE CLOSELY, OR THE EGG WHITES/MERINGUE WILL BURN!
Remove the cheesecake from the oven and place on a wire rack to allow the meringue to cool - approximately 5 minutes.
Place the cheesecake back into the refrigerator and keep chilled until time to serve.
Before serving, cut the cheesecake in 2 inch pieces and add a sugared lemon slice on the side.