In a large stand mixer bowl fitted with a dough hook attachment, add the flour, salt, egg, and oil. Set aside.
In another small bowl, combine the warmed water/milk, sugar, and dry yeast. Stir and let the yeast become foamy.
Once yeast has been activated, add the mixture to the flour mixture, turn on the mixer to low-medium speed. Knead for about 7-8 minutes, until the dough is smooth and shiny. The dough will feel quite soft.
Transfer the dough to a lightly greased bowl, cover, and let it double in size in a warm location.
Divide the dough into 10 equal portions.
Roll the dough into a rectangle/oval about 7" by 3".
Brush the surface with a little beaten egg.
Add about 1 tablespoon pork floss and 1 tablespoon chopped green onion over top of the dough.
Roll the dough lengthwise into a long cigar, pinching the seams.
With the dough facing you like the letter "I," use a sharp knife and make a slit in the middle of the dough, leaving about 1 inch uncut at the top. You will have two pieces, but it will still be joined at the top.
With the exposed ends showing, carefully lay each half of the dough over each other, similar to braiding. (Beware, this can get a little bit messy).
Grab each end of the dough and gently twist the dough, pinching and tucking the ends into the centre of the bun from underneath.
Place the bun onto a parchment-lined baking sheet. If any filling has fallen out, gather it up and place onto the bun. Repeat with the remainder.
Loosely cover the buns with plastic wrap and leave until slightly puffy.
Preheat oven to 350°F/177°C.
Let the buns rise for another 20 minutes, until dough is slightly puffy.
Brush the tops with the remaining beaten egg and sprinkle sesame seeds if you wish.
Bake at 350°F/177°C for 20-22 minutes, until golden brown. Serve warm or at room temperature.