Preheat oven to 350°F. Line10x15 inch jelly roll pan with parchment paper then grease with butter or shortening.
Sprinkle a large rectangle of parchment paper or a thin kitchen towel with powdered sugar and set aside.
In a small bowl, whisk together cake flour, cocoa powder, baking powder, and salt. Set aside.
In another small bowl, combine the buttermilk, vinegar, and vanilla extract.
In the bowl of a stand mixer fitted with a whisk attachment or using a large bowl and an electric hand mixer, beat the eggs with brown sugar for five minutes until fluffy and aerated. Next add in the oil then buttermilk mixture and red food coloring beating again.
Add the flour mixture in two increments and beat on low speed until well combined, about 2 minutes.
Pour the batter into the prepared pan and spread evenly to reach all edges. Bake for 11-13 minutes, or until the top of the cake springs back when touched.
Immediately turn the cake out onto the previously prepared parchment paper or kitchen towel and peel off the attached paper on the cake. Very carefully roll up the cake and paper (or towel) together, starting at the narrow end. Place the cake, seam-side down, on a cooling rack to cool to room temperature, about 45 minutes.
While you wait for the cake to cool, prepare the filling.