Step by step

Flatten out each disc with a spoon and place the filling inside

If you find it hard to digest onion, leave it in some milk for half an hour before using: it will become sweeter and more delicate, and above all much more digestible.
In China there is a dish similar to this one called Gwa-bao, and is also a ‘bun’ filled with pork. The difference is that the pork in this case is not steamed but rather fried. The Gwa-bao are "cousins" of Mantou, common steamed dumplings and meat, which are also very popular in China.