To make the dough - mix flour, sugar, baking powder, salt and pepper and yeast. Add oil and mix well. Add water, knead for at least 5 minutes then cover and leave for room temperature for 1 hour. Note: Leaving the dough for too long can make it blow and the buns will be thin and tear instead of thick and fluffy.
For the filling - soak vermicelli in warm water for 10 minutes then drain and cut into 2cm lengths.
Mix all filling ingredients in a bowl and knead until slightly sticky.
Cut the dough into 8. Using a rolling pin, make a piece of dough into a 12cm diameter disc. Put 1/8 filling on the middle of the disc and wrap all around to make a ball shape. Twist the top of the joint. Make 8 ball buns in the same way.
Put the buns on a baking paper (or lettuce leaf) lined steamer. Steam them on high temperature for 15 minute.
Serve with soy sauce, vinegar, chilli and sesame oil.