Preheat the oven to 350 degrees F.
Line two cupcake pans with parchment cups.
In a medium bowl, combine the cake flour, black cocoa powder, baking soda, and salt.
In a large bowl, add the butter and sugar. Use an electric hand mixer to beat until light and fluffy, about 2-3 minutes.
Add the oil, egg yolks, vanilla, and vinegar, and mix until well combined.
Add the dry ingredients to the wet and mix on low speed until just combined.
Add the buttermilk and sour cream and mix.
In a separate small bowl, add the egg whites and use an electric hand mixer to beat until stiff peaks form.
Using a rubber spatula, fold the whipped egg whites into the batter until fully combined.
Using a 3 tablespoon cookie scoop, add one scoop to each parchment cup.
Bake the cupcakes one pan at a time for about 18-20 minutes until the centers spring back when touched.
Allow the cupcakes to cool completely before decorating.