Mantou - baozi - chinese steamed buns

Ingredients

Ingredients:

• (a) old dough - about 300g gram
• 200g flour
• a pinch salt
• 1/2tsp yeast
• 110g water
• (b) main dough - about 770g
• 200ml cold milk
• 350g flour
• 5g yeast
• 80g sugar
• 1/8tsp baking soda
• 1tsp bread improver/ bread softerner (optional)
• 100g old dough
• 15g oil