Preheat your oven to 180°C. Place the muffin cups in a muffin pan (if using) or grease a muffin pan well.
Place the sugar, flour, salt, bran, bicarb and cake mix in a large mixing bowl. Give the mixture a quick stir to distribute the ingredients evenly.
Add the oil, egg, milk and vanilla extract. Mix until just combined. If you are not using the mixture immediately then cover the bowl or transfer the mixture to an airtight container and pop in the fridge.
Divide the mixture between the 12 muffin cases. Bake for 18-20 minutes or until an inserted skewer comes out clean. Serve warm or cool with butter or just as they are.