Preheat the oven to 350°F. Line 2 (12-cup) standard muffin pans with cupcake papers. Set aside.
In a small mixing bowl, add the all-purpose flour, unsweetened cocoa powder, baking powder, baking soda, and salt. Stir to combine.
In a large mixing bowl, using a handheld mixer on medium speed, cream together the unsalted butter, vegetable oil, and granulated sugar for 1 to 2 minutes or until light and fluffy.
Add the eggs, one at a time, to the butter mixture. Make sure to fully incorporate each egg before adding the next.
Add the vanilla extract, green liquid food coloring, and white vinegar, and beat just until the mixture is smooth. This will take another 1 to 2 minutes.
Next, you will alternate adding the dry ingredients with the buttermilk to the butter mixture. Start by adding ⅓ of the dry ingredients to the bowl with the butter mixture. Beat on low for 30 seconds or just until the dry ingredients are incorporated. Then you will add ½ of the buttermilk and beat on low for another 30 seconds or just until incorporated. Repeat adding the second ⅓ of the dry mixture, followed by the other ½ of the buttermilk, and ending with the last ⅓ of the dry mixture. Make sure to mix each addition just until the ingredients are incorporated. You do not want to overmix your cupcake batter, or your cupcakes will be dense and tough.
Fill each cupcake paper ⅔ full with batter. Bake for 20 to 22 minutes or until a toothpick inserted into the center of a cupcake comes out clean. Allow the cupcake to cool in the pans for 5 minutes, then transfer the cupcakes to a wire rack to cool completely before frosting and serving.