Preheat the oven to 350° F.
Cream the shortening and sugar together in a large mixing bowl.
Add the eggs and vanilla. Stir to combine.
Sift the cake flour, salt and cocoa powder together in a separate mixing bowl.
With the mixer running on low, add one third of the dry ingredients. Mix to combine.
Add 1/2 cup of the buttermilk and continue to mix.
Continue to alternate with 1/3 of the dry ingredients and the remainder of the buttermilk, ending with the last 1/3 of the dry ingredients.
Add the red food coloring and beat on medium until the food coloring is thoroughly mixed. Turn the mixer off.
In a large nonreactive dish or measuring cup, dissolve the baking soda with the vinegar. This will fizz for a moment! Once the fizzing stops, gently fold the soda and vinegar mixture into the bake batter.
Pour the batter into two greased and floured 8-inch round cake pans. Bake for 30-35 minutes until a toothpick inserted near the center of the cake comes out clean.
Allow the cake layers to cool in the pan for 10-15 minutes before removing them. Allow the layer to cool completely before frosting.