For the pau skin: Sift flours into a mixing bowl. Add sugar, salt, yeast and baking powder. Stir well to combine. Add water and oil. Process with a dough hook fitted to the machine until a soft and pliable dough is formed.
Cover with a damp tea towel and leave aside to proof for 30 minutes.
Put dough onto a lightly floured tabletop and knead for a short while. Divide dough into 10 equal pieces.
Roll each piece of dough into an oval, then roll out flat. Brush lightly with canola oil and fold up into a half-moon. Arrange each piece of half-moon dough on a small piece of grease-proof paper. Leave aside to proof for 15 minutes.
Steam the pau over medium heat for 10 minutes.
Remove and add filling of your choice into the open faced pau.