Preheat the oven to 325 degrees F. Coat two 9-inch cake pans with cooking spray and line the bottom and sides with parchment paper. Soak the cake baking strips in water.
Sift the flour, cocoa powder, baking powder, baking soda, and salt into the bowl of a mixer, then stir in the sugar.
In a separate bowl, use a whisk or hand blender to combine the buttermilk, vegetable oil, eggs, vanilla, vinegar, diluted coffee, and red food coloring. If desired, add more food coloring for a more intense red color.
Turn the mixer to low speed. Slowly mix the wet ingredients into the dry ingredients until the mixture is just combined. Be careful not to overmix your batter.
Pour the batter evenly between the two pans. You can use a kitchen scale to measure the pans to make sure they have the same amount of batter.
Squeeze out the excess water from the baking strips and secure then around the cake pans.
Bake for 60-65 minutes, or until the cakes are springy to touch and a toothpick comes out clean or with a few crumbs attached.
Let the cakes cool in the pans for 20 minutes, then carefully invert the cakes onto a cooling rack, and cool completely.