I preheat the oven to 350°F (175°C) and line a 12-cup muffin pan with liners. I whisk 1 ¼ cups flour, 2 tbsp cocoa, ½ tsp baking soda, and ½ tsp salt. In another bowl, I beat ½ cup oil, ¾ cup sugar, and 1 egg, then add ½ cup buttermilk, 1 tsp vanilla, 1 tsp vinegar, and 1 tbsp red gel coloring. I mix in dry ingredients, fill liners ⅔ full, and bake 18–20 minutes until a toothpick is clean, cooling on a rack for this simple recipe.