I found a sensible-looking recipe online. Their dough recipe was used more or less unchanged (save for the substitution of butter for lard; I don't tend to have lard hanging around). The filling was shredded chicken (put through food processor), about a tablespoon of minced garlic, about a tablespoon of minced ginger, about one and a half tablespoons of pureed lemongrass, and some mushrooms (a tin). (All measurements are approximate. Very approximate.)
Stir-fried the chicken and its accompaniments, made the dough, pressed pieces of dough out into circles by hand, filled the circles. The recipe says not to seal the packets so I just attempted to gather them together at the top.
Lesson learned (1): don't put the buns into the steamers to rise. You will wind up with a bunch of buns so closely packed as to be inseparable. They also don't steam so effectively if they are that closely packed. Letting them rise for the prescribed 30 minutes and then putting them in the steamers would probably have been a better plan.
Lesson learned (2): the dough could have done with being just a touch sweeter than it actually was. I'm not sure that adding more sugar in the fermentation phase would have achieved this; maybe mixing in a little sugar along with the flour would have done.
Lesson learned (3): The filling was pretty damn good. It's just possible a little bit of coriander might have improved it (though in my view, a little coriander improves almost anything savoury), and maybe a bit more ginger, but it was fine as was. However, four chicken breasts minced plus the above-mentioned accompaniments produces about twice as much filling as you can get into the amount of dough made (the remainder will be part of my lunch today).
Lesson learned (4): I am not sure why the recipe says not to seal the buns at the top, since the filling, being mostly cooked already at this point, isn't going to expand to any noticeable degree. I reckon they'd've worked better sealed -- may try that next time.
I have a jar of Char Siu sauce here, so will acquire some pork at some point and try making Char Siu pork buns...