In a stand mixer attached with a dough hook, combine all ingredients except for butter.
Knead until it comes together in a ball of dough.
Add butter. Knead until it is fully incorporated into the dough.
Pause to do a windowpane test. Pinch a small piece of dough — using both your thumbs and index fingers, gently stretch dough in opposite directions. If you can stretch the dough to resemble a windowpane without it breaking or tearing, the gluten is sufficiently developed. If not, continue to knead another 3-5 minutes and do another windowpane test.
Place dough in a deep bowl. Rest in a warm place (turned off oven with a bowl of hot boiling water placed on oven floor) for 45 – 60 minutes.
Degas dough and divide into 9 portions and rest for 15min covered.
Take a dough and roll into a rectangular shape. Spread mayonnaise and add pork floss. Roll from top to bottom and seal.
Flatten slightly and make 2 slits. Braid and roll to tuck 2 ends to the bottom. Place in paper cuppies. Rest in a warm place for 45 – 55 minutes.
Egg wash and add chopped spring onions and sprinkle with sesame seeds.
Bake in a preheated at 180°C for approx 15 minutes depending on individual oven