Break the egg into a bowl, and add the milk, salt, brown sugar, oil, plain flour and baking powder, in that order, and whisk to mix.
Pour the mixture into cupcake cases, and place the cases on the enamel tray.
To prevent moisture droplets falling on the buns as they cook, spread kitchen paper or muslin over the wire shelf, and slot it into the upper shelf position.
Slot the enamel tray into the lower shelf position, and cook on Steam 1 for 15 minutes.