Next, add the cooled tangzhong to the rest of the dough ingredients in a stand mixer bowl fitted with a dough hook and knead until it becomes smooth. It shouldn’t be dry or sticky.
*Note: if using active dry yeast, bloom in lukewarm milk first before adding to the flour mixture.
Kneading the dough for long enough is important as this action produces gluten, which makes the dough smooth and elastic.
Transfer the dough to a lightly oiled bowl. Cover the dough and let it rest in a warm location, until doubled in size, about 1 hour, depending on how warm your environment is.
Divide the dough into 10 equal portions, and roll each portion into a ball. Repeat with the remaining.
Tip: To shape, gently cup the dough with your hand, press slightly on the dough while moving your hand in a circular motion.
Cover with plastic wrap or a damp cloth and let it rise again until puffy, about 30-40 minutes.
Brush the tops of the buns with a little milk.
Towards the end of the proofing time, preheat oven to 350°F/177°C.
Bake the buns at 350°F/177°C for 18-20 minutes, or until an instant thermometer registers 190°F/88°C.