Preheat the oven to 350°F. Position an oven rack in the lower-middle of the oven.
Add the sugar to a food processor and pulse until fine and powdery. Remove 1 cup of the sugar and set aside.
Add the cake flour and salt to the remaining sugar in the food processor. Pulse until combined and light.
In a large mixing bowl, beat the egg whites and cream of tartar with a stand mixer or hand mixer fitted with a whisk attachment until light and foamy, about 1 minute.
Reduce the mixer speed to medium. Gradually add the reserved 1 cup of sugar and beat until soft peaks form, about 5–6 minutes.
Add the vanilla extract and mix just until combined.
Gently fold the flour mixture into the egg whites, about ¼ cup at a time, using a spatula. Continue until all the dry ingredients are incorporated.
Spoon the batter into an ungreased 9- or 10-inch tube pan. Gently tap the pan on the counter to remove large air pockets.
Bake for 35–40 minutes, until the cake is golden brown and a toothpick inserted into the center comes out clean.
Remove from the oven and immediately invert the pan. Allow the cake to cool completely upside down, about 2–3 hours.
Run a knife around the inner and outer edges of the pan to loosen the cake. Carefully remove it from the pan.
Slice and serve as desired with powdered sugar, whipped cream, or fresh berries.