Preheat oven to 350 degrees F. Butter 2 medium sheet pans, or 2 (8-inch) round cake pans.
In a bowl, sift flour and salt together. In an electric stand mixer, combine butter and sugar at medium speed. Add vanilla, then the eggs, 1 at a time, and then cocoa powder. Reduce mixer speed to low. Stream in half of the buttermilk, then slowly add half of the flour mixture, then the rest of the buttermilk and remaining flour. In a separate bowl, mix vinegar and baking soda, and mix into the batter. Add red food coloring and combine well. Once thoroughly mixed, divide batter evenly between cake pans. Bake for 30 to 35 minutes, or until toothpick inserted in the center comes out clean. Remove from the oven and allow to cool in the pans. Slice, as desired, and serve.
This recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. The FN chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.