01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners.
02 - Whisk together flour, sugar, cocoa powder, baking soda, and salt in a medium bowl.
03 - In a large bowl, whisk oil, buttermilk, egg, vanilla, vinegar, and red food coloring until smooth.
04 - Add dry ingredients to wet and mix until just combined, avoiding overmixing.
05 - Divide batter evenly among liners, filling each about two-thirds full.
06 - Bake 18–20 minutes, until a toothpick inserted in the center comes out clean.
07 - Cool cupcakes in the pan for 5 minutes, then transfer to a wire rack to cool completely.
08 - Beat cream cheese and butter until creamy. Add powdered sugar, vanilla, and salt; beat on low until combined, then increase speed until fluffy.
09 - Once cooled, frost cupcakes generously using a piping bag or spatula.