Preheat the oven to 350°F. Grease and flour the inside of a 10 to 12-cup capacity Bundt pan and set aside.
Sift together the cake flour, all-purpose flour, baking soda, and salt. Set aside.
In the bowl of an electric mixer, cream together the butter and sugar until light and fluffy. Add the oil and mix to combine. With the mixer on low, add in the cocoa, vanilla, red coloring, and eggs – one at a time. Stop the mixer and scrape down the bowl.
With the mixer on low, add in half of the dry ingredients followed by the buttermilk and vinegar. The batter should be plenty pink by now. If it seems too light, add another few drops of gel food coloring and mix to combine.
Add the second half of the dry ingredients and mix until combined.
Scrape the batter into the prepared pan. Bake in the oven for 50 to 60 minutes, or until a wooden skewer inserted into the center of the cakes comes out clean.
Immediately set a timer for 20 minutes. When it goes, carefully unmold the cake from the pan. Gently loosen the edges of the cake with a flexible spatula. Place a wire rack or cake plate on the top of the cake. Using oven mitts, flip the cake upside. Give a few taps until you feel the cake loosen and remove the pan.
Allow the cake to continue to cool before adding the frosting and serving.