Preheat oven to 350 F. Prepare a 10-inch tube pan by spraying with nonstick cooking spray and dusting with flour. Set aside.
Sift cake flour and salt onto a piece of parchment paper. Set aside.
In the bowl of a stand mixer fitted with a whisk attachment, whip sugar, cream of tartar, and egg whites on low speed for 5 to 6 minutes, until sugar is dissolved. Add in the vanilla, then turn the speed up to high and whisk until stiff peaks form, about 5 more minutes.
Sift flour mixture into the bowl and fold in gently with a rubber spatula.
Add the batter to the prepared cake pan. Bake for 35 to 40 minutes, or until a toothpick inserted into the cake comes out clean. Remove the cake from the oven and immediately run an offset spatula between where the cake meets the pan on the outside edge and in the center.
Allow the cake to cool in its pan, inverted onto a wire rack, for 10 minutes, then flip it and let cool completely until ready to serve. Pair with whipped cream, jam, and/or fresh fruit if desired. Cake can be stored covered at room temperature for up to 2 days.