Heat oven to 350?. Greese and flour two 9 inch cake pans. In a medium bowl combine cake flour, cocoa and salt; set aside. With electric mixer on medium beat together 1 1/2 cups sugar and vegetable oil. Beat in eggs, one at a time. Add food coloring and 1 tsp vanilla. Alternately beat in flour mixture and buttermilk, beginning and ending with flour mixture. In a small bowl stir together vinegar and baking soda; beat into batter. Evenly divide batter into pans. Bake 28-32 minutes, or until wooden pick inserted into center comes out clean. Cool pans on wire racks 10 minutes. Carefully invert cakes onto racks; cool to room termerature.

Frosting

In top of double boiler over simmering water, beat on low speed 1 1/2 cups sugar, egg whites, cold water and corn syrup. Beat until mixture peaks stiffly, about 7 minutes, beginning on low speed, then to medium, then to high. Add remaining vanilla and beat until frosting is spreadable. With rubber spatula, stir in melted chocolate; frost with metal spatula. Refrigerate until ready to serve.