[To make the dough:] Put (A) in a small bowl and leave aside to froth. Sieve (B) into a basin. Make a hole in the middle and pour in the yeast mixture.
Add in (C) and mix well. Add the water to form a soft dough. Rub in the shortening. Leave dough aside to prove for 30 minutes.
[To make the filling:] Heat oil and stir-fry diced onions. Add in char siew. Mix in seasoning and blend well and add in sesame seeds. Remove filling and leave aside to cool. Keep in the refrigerator to slightly harden the filling.
[To make chan pau:] Roll out dough into equal portions. Take one portion, flatten slightly and wrap up with filling and pleat into pau shape.
Place on greaseproof paper and set aside for 20 minutes.
Brush pau with egg glaze. Bake at 150 to 160 ºC for 15 to 20 minutes.
Immediately after baking, brush pau with sugar oil for a nice sheen. (To make sugar oil, place water and sugar in a small container and leave till sugar dissolves.)