Heat milk until it is between 100-110F and place 2g of active dry yeast in*
Measure all the ingredients in order listed and mix. I use the “dough” function on my bread machine, which is a 15 minute mixing cycle.Add walnuts + raisins in the last 3 minutes of the mixing cycle (if using bread machine)** Don’t worry if not all the add-ins are incorporated fully.
With your hands, gently knead in unincorporated walnuts and raisins. Form dough into a ball. Allow dough to rest for 1-2 hours until doubled in size.
Flatten dough with rolling pin. Roll out dough into a rectangle (11" x 16") and 1/4" thick
Starting from the top of the rectangle, tightly roll down the dough until it forms a log.
Cut log into pieces about 2” wide.
Place mantou dough in steamer lined with parchment paper about 1” apart. Allow dough to rise a second time until double in size (1-1.5 hours).
Start heating water (from cold) in the steamer at medium-high heat. Once water starts to boil, set timer for 15 minutes and steam mantou for 15 minutes. When the 15 minute timer goes off, turn off heat and let mantou sit in steamer for another 5 minutes before opening the lid.
Enjoy the mantou fresh out the steamer (best in my opinion!). Otherwise I recommend freezing the uneaten ones after they've cooled. To reheat, simply steam for 10 minutes to have piping hot steamed buns.