Preheat oven to 350°F for 15 minutes before baking cake.

In a mixing bowl, sift together flour and salt. Set aside.

In a separate mixing bowl, cream butter and sugar until light and fluffy, on medium speed for three minutes. Add eggs, one at a time, beating well after each addition.

In a small bowl, stir together cocoa powder, food coloring and vanilla extract. Beat this into the butter mixture.

Stir 1/3 of the flour mixture into the butter mixture, alternating with 1/2 of the buttermilk, another 1/3 of flour, the remaining buttermilk, and the remaining flour mixture; stir just until blended.

In a cup, combine vinegar and baking soda. Mixture will fizz. Stir this into the batter and combine well.

Divide batter evenly between two greased and floured 9-inch round cake pans.

Bake for about 22 to 28 minutes until a toothpick inserted into center comes out clean.

Allow cakes to cool in pans on a wire rack for 10 minutes. Run a blunt knife along edges of pan to free cake; remove cake gently from pans and cool completely on wire rack.

Frost with any of the following icings: Cream Cheese Icing, Buttercream Frosting or Seven-Minute Frosting.