Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a medium bowl, whisk together the flour, cocoa powder, and salt.
In a large bowl, beat the sugar and vegetable oil until well combined. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In a small bowl, combine the buttermilk and red food coloring. Mix well.
Gradually add the dry ingredients to the sugar and oil mixture, alternating with the buttermilk mixture. Begin and end with the dry ingredients. Mix until just combined.
In a small bowl, mix the baking soda and vinegar. Add it to the cake batter and stir until well incorporated.
Divide the batter evenly between the prepared cake pans. Smooth the tops with a spatula.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center of the cakes comes out clean.
Remove the cakes from the oven and let them cool in the pans for 10 minutes. Then transfer them to a wire rack to cool completely.
Once the cakes have cooled, you can frost and decorate them as desired with cream cheese frosting, buttercream, or your favorite frosting.