Chinese steamed buns
I know this query has been raised before, but while I don't recall seeing those in the Chinese bakeries, I have seen them in the refrigerated section of the Chinese supers like 99 Ranch. I can't vouch for how supple they will be as I'm imagining the pillowy steaminess of those buns encasing the unctuous pork, cucs, scallions and hoisin sauce. Go with the Persian cucs that have become very common in the markets nowadays.
Here's a previous thread on this topic:
There have been some other threads about searching for dishes similar to Momofuku's pork buns at local restaurants: