Fill the steamer with tap water.
Mix the dry ingredients well, then add the water. Using a dough hook attachment, knead in a stand mixer on low for approximately 8 minutes. Different brands of flours have different hydration levels so you may need more water to get a smooth dough: start with 125g of water then gradually add more, 1 teaspoon at a time, if necessary.
You will know that the dough has been sufficiently kneaded once it becomes a smooth ball that does not stick to the mixing bowl or to your hands. After stopping the stand mixer, knead with your hands for another minute or so. (Alternatively, if you've missed your gym workout, you can do the kneading by hand- just remember to rest the dough for 10-15 minutes after the ingredients have combined to form a rough mixture.)
After mixing, you can move on straight to shaping the dough. For this post, we'll just focus on the simple mantou shapes: oblong and round. Divide the log of dough into 2, then cut each log into 6 pieces, giving you 12 in total. You can steam the oblong dough pieces as they are or roll them into round balls before steaming. To get round mantou buns, pull and tuck the ends of the dough so that the seams are all facing downwards- you will get a round-ish top and just roll each bun (on a floured surface, parchment paper or Silpat mat to prevent sticking) till smooth. Note: if you don't have a smooth ball of dough here, your mantou won't miraculously become smooth post steaming!
To prevent the dough from sticking to the steamer, either place the dough onto small pieces of parchment paper (you can substitute with cupcake wrappers if lazy to cut up parchment paper) or oil the steamer- you will need to re-oil every time you add new mantous to the steamer. Personally, I find using parchment paper makes it easier to remove the mantous after steaming.
Place the buns into the steamer, ensuring that there is at least 1.5 inches in between each mantou if you don't want to stick to each other after steaming. Allow to rest for 20 (tropical weather of 30C/ 86F) to 30 minutes (25C/ 77F weather). You will know the dough is sufficiently rested when the buns are very smooth, have increased about 40-50% in size (they will not double in size) and spring back after being pressed. If you're unable to steam all the mantou buns at 1 go, store them in the fridge to stop them from overproofing- this is particularly important in warm countries as heat expedites the proofing process.
Turn on the fire to high, then reduce to medium-low once the water is at a rolling boil. After 10 minutes, switch off the fire. The steamed green tea bread is best enjoyed warm. If the mantous aren't as smooth as you'd like, scroll back up my mantou troubleshooting section which identifies common mantou making mistakes.
The steamed matcha buns are ready to be enjoyed!