Combine egg whites and room temp. water in a mixer and start on medium speed.
As the eggs get frothy, add cream of tartar, salt, and vanilla extract. Beat until you see soft peaks.
Increase the speed to medium-high and add sugar one tablespoon at a time. Beat until you see stiff peaks.
Transfer to a bigger bowl. Sift the sugar and flour at least 3 times previously to avoid clumps. Sift over your batter in batches then fold the sugar/flour mixture into the batter.
Transfer into a tube cake pan. Spread the batter evenly with an offset spatula.
Remove batter from the top of the pan with your finger. Then take a knife and move it through the batter.
Bake for 35-40 minutes on 350 F. with the rack in the middle of the oven.
Invert the pan to let the cake cool. Then take a frosting spatula and glide this around the outside of the cake, allowing it to fall out of the pan. Spin the spatula around the bottom of the pan and use a smaller knife to remove the center tube.