Pre-heat oven to 325° F. Line an 18 cup muffin tin with 14 liners. Set aside.
Sift together ¼ cup sugar, salt, and cake flour.
In a mixing bowl or stand mixer, beat the egg whites, water, and cream of tartar until it becomes foamy. Gradually add the remaining sugar as you beat on medium-high speed. When soft peaks begin to form, add the vanilla.
Slowly fold the flour into the batter. Do not add it all at once because you want an airy batter.
Add batter to cupcake liners and fill about ¾ full. Place in the oven and bake for 20 minutes.
Remove from oven and cool before adding the berry topping.