Separate the eggs while they're still cold from the refrigerator -- the yolks and whites will be more firm and separate more easily. Use an egg separator if you like, but pouring the egg into your hand and letting the whites slip through your fingers works just as well (and saves washing a utensil).

Do not allow any pieces of yolk to mix with the whites, or the whites will not beat to maximum volume. To ensure that the whites do stay free of any yolks, separate each egg over a small bowl, then pour the whites into a scrupulously clean large bowl (free of even the faintest trace of grease).

Beat the whites with a mixer on high speed until they're foamy, then add the cream of tartar and salt.

Continue to beat the egg whites on high speed until soft peaks form, then add the sugar gradually. (Add more sugar only when the previous addition is dissolved.)

When stiff peaks form, the whites will look shiny, moist, and snowy, and the peaks will hold high when you lift the beater. Be careful not to overbeat the whites -- lightly underbeaten egg whites will work, but overbeaten whites will make a tough cake.

Sift or sprinkle the flour a little at a time over the beaten egg whites. Then, with a large spatula, use large sweeping motions to fold the flour into the eggs. The goal is to work in the dry ingredients without deflating the whites.

Gently scrape the batter into an ungreased pan -- preferably an angel food tube pan with a removable bottom. Don't bother to use a nonstick pan -- the batter needs to cling to the sides of the pan as it cooks, and will do so despite the surface. Smooth the top of the batter evenly. If you're using an angel food pan, run a knife through the batter to break up any air pockets that may have formed when the batter was poured into the pan.

Place the cake in the center of the oven for even baking. Don't open the oven door until the baking time is up (or very nearly so); the fragile egg whites may begin to deflate as cool air rushes into the oven.

Cool the cake upside down so that the weight of the batter doesn't deflate the cake while it's still warm. If your pan does not have "feet," invert it by placing the center hole on the neck of a wine bottle.

To remove the cooled cake from the pan, run a narrow metal spatula or thin knife around the edges, including the center tube; take care to dislodge as little golden crust as possible. If your pan has a removable bottom, push it up to dislodge the cake, then use the same spatula method to loosen the cake from the bottom of the pan. If not, or if you are using another kind of pan -- such as a jelly roll pan -- line the bottom with parchment paper or wax paper before spooning the batter into it.

Cut the cooled cake with a serrated knife using a gentle sawing motion. There's no need to bother with pronged cutters made especially for angel food cake -- they don't work nearly as well.

Store angel food cake, tightly covered, at room temperature for up to 2 days, or freeze for up to 4 weeks.