Preheat oven to 375'
Put egg whites and water in a very clean large metal bowl and swirl it over simmering water until barely warm.
Sift together flour and 1/8 cup of sugar. When you think you've sifted enough, sift it one more time.
Beat whites in a standing electric mixer on medium speed until frothy. Add vanilla, cream of tartar, and salt. Increase speed to medium-high and beat just until soft peaks begin to form.
Gradually beat in the remaining 1/2 cup of sugar, 1 tablespoon at a time, occasionally scraping down the side of the bowl. Increase speed to high and beat until stiff, glossy peaks form. DO NOT OVERBEAT.
Sift 1/3 of the flour mixture over the whites. Beat on low speed until just blended and then sift and beat in the remaining flour in 2 more batches.
Gently spoon the batter into liners inside a muffin tin and smooth the tops. Run a spatula or knife through the batter to eliminate any large air bubbles.
Bake in the lower third of oven until golden and a tester comes out clean, 15-18 minutes. Let cool before frosting