Re: Bao question
I've seen this done two ways,
One a Portland pierogi truck has three vertical dumpling steamers and rotate them through from start to finish. Their items are smaller than the standard Bao(think golf ball rather than softball), and they sell multiple at a time. So they have a hard time keeping up in a rush.
The second is from a booth vendor who uses a dumpling steamer along with a 6" hotel pan and two 4" slotted pans over to hold them. I would imagine the same system would work but you may need to test it a few time at different temps to find the sweet spot.
I would defiantly not make those to order though. Plan for your average amount of fresh to start the day and look into a blast freezer and a vertical freezer for the rest, steaming isn't going to change the consistency if they don't take a long time to cool. That way you save any uncooked leftovers and have plenty on hand for larger events.