• Preheat the oven to 325 degrees F. Line a muffin pan with 24 paper liners.
• In a small bowl or a 2 cup glass measure, stir together cocoa powder, boiling water and liquid food coloring. Set aside to cool slightly. Note: If using a thick gel color, mix only the cocoa powder and water and add a few drops of gel later.
• Stir the buttermilk and vanilla into the cocoa mixture.
• In a mixing bowl, cream the butter and shortening (or oil) until smooth. Scrape down the bowl and add the sugar. Beat until the mixture is light and fluffy. Add the eggs, one at a time, beating well after each addition. Beat in the salt.
• With the mixer on low, add the flour and the buttermilk mixture alternately to the egg mixture in three separate additions, beginning and ending with the flour mixture. Beat until incorporated. If you are using a thick gel rather than liquid color, add a few drops until you get a deep red hue.
• In a small bowl, combine the vinegar and baking soda and stir until the baking soda dissolves; the mixture will fizz. Add to the batter and stir until just combined.
• Divide the batter among the prepared pans and smooth the tops. Bake until a toothpick inserted in the center of each cake comes out clean, about 15-20 minutes for cupcakes, rotating the pans halfway through the baking time.
• Transfer the muffin tin to a wire rack and let cool for 5 minutes or so, then remove cupcakes from pan and allow to cool on rack.

Cream Cheese Frosting

• With an electric mixer, beat the butter and cream cheese until light and fluffy.
• Gradually add the confectioners' sugar, scraping bowl and beating. Beat in the vanilla. Add lemon juice for a little more tartness if desired.