Preheat oven to 350°F.
Have a 10-inch angel food tin for this. This is a center tube, loose-bottom cake tin with the outside diameter of the top opening measuring 10 inches and with sides approximately 4⅜ inches high. Do not butter the tin. It is critical that when you "hang" the cake after baking, it must stick to the tin and not fall out. For hanging, you can use a wine bottle with a plastic band on the top neck that keeps the hanging cake tin from tilting.
Sift together into the bowl of an electric mixer the cake flour and sugar.
Make a well in the center of the flour-sugar mixture and place in it the yolks, cold water, lemon zest, lemon juice, vanilla, and salt.
Mix together then beat to the ribbon stage. You can use a KitchenAid mixer with the balloon whip and set the speed at low/moderate or #4 out of 10 settings. It will take 8 or 10 minutes.
Transfer batter to a large bowl then wash the mixer bowl well and place in it egg whites and cream of tartar. Using balloon whip at low/moderate speed, beat to soft peaks. Sprinkle in the sugar, one tablespoon at a time while continuing to beat. When all sugar is in, beat mixture to stiff peaks. It is important that the whites be beaten to the proper stiffness so don't stint on this.
Fold ⅓ of the whites into the yolk mixture, then fold in the balance.
Pour the batter into the tube pan. With a thin knife, gently cut through the batter to break any air bubbles. Put into preheated 350°F oven and bake 45-50 minutes or until a cake tester comes out clean. The cake should rise to an inch or two above the rim. Sometimes it cracks or develops furrows.
Immediately invert the pan over the thin-necked bottle. Let the cake cool suspended. When cool, ideally the cake will have shrunk level with the rim of the pan. Carefully cut around sides and remove the cake from tin. If not using right away, freeze until the day before serving.