Cake: Cream together butter, sugar and eggs. Make a paste of cocoa and food coloring. Add the paste to the creamed mixture. Mix salt and vanilla in buttermilk and add a;ternately with the flour. Mix soda and vinegar separately, add last, folding in. Do Not Beat after adding soda mixture. Bake at 350~ for 30 minutes. Icing: Boil together milk and flour until thickened. Let stand until cool. Cream together butter, sugar amd vanilla. Add milk and flour mix and beat very well. (The longer you beat it the better it gets)