Preheat oven to 350. Line or spray cupcake tins. Place egg whites in a large bowl and mix until eggs are frothy approx. 1 min. Add cream of tartar, salt, and vanilla. Mix until egg whites are almost stiff, aprox. 4 min. Add 1 C. of sugar gradually while mixing. Scrape bowl. Mix flour and remaining 1/2 c. sugar together and spoon 1/4 of mixture over egg whites, folding gently in between each addition. Pour batter in to tins. Bake 20 to 25 min. or until tops are golden brown and cracks are very dry. Cool completely, frost.