7-Minute Frosting

1 cup sugar
1/4 teaspoon salt
1/2 teaspoon cream of tartar
2 egg whites
3 tablespoons water
1 teaspoon vanilla

Combine all ingredients except vanilla in a stainless steel heavy-bottomed saucepan.
Place mixture over medium-low heat and beat with an electric hand mixer constantly for 5-7 minutes, or until stiff peaks form when beaters are removed.
Remove from heat and stir in vanilla.

Enough to cover 1/2 of a layer cake.