In a bowl measure out flour, baking powder, salt and cocoa powder. Set aside. In another bowl whisk the butter and sugar together until creamy. Add the egg to it and the vanilla extract.
In a separate bowl mix milk and 1 tblsp vinegar together. Let the milk split and add in the red food colouring to it.
In a small bowl add together the remaining vinegar and baking soda. Let it bubble and add to the egg mixture. Add all the flour mix to it followed by the red colored mix. Mix until no lumps. Do not over mix
Pour into a prepared cupcake tray and bake at 170 degree centrigrade for 20 minutes or until a skewer comes out clean.
While the cupcake is baking, make your frosting. In a large bowl, mix together cream cheese and butter until thick and creamy. Add in the lemon zest and vanilla and add all the icing sugar. Whisk until smooth.
Once the cupcakes come out of the oven. Cool. And then frost and serve.