Sourdough Steamed Buns (Bao/Mantou)

• I strongly encourage you to have an active starter that is at least two-month old before you attempt to make this sourdough steamed buns recipe for the best result. I personally prefer using a sweet stiff starter for enriched dough.

If using regular starter, prepare the levain:

• If you prepare the levain overnight: Mix 30 grams of your active starter with 100 grams of all-purpose flour (not bread flour) + 100 grams water. This will take about 7-8 hours to peak, depending on the temperature and the strength of your starter at around 78 F (26 C)
• If you prepare the levain on the same day: Mix 70 grams of starter + 70 grams of all-purpose flour (not bread flour) + 70 grams of water. This 1:1:1 ratio will peak at about 4 hours at 78 F (26 C)
• Remember that you want to use your starter at its peak, meaning it has doubled or tripled when you are ready to use it

Prepare the dough (for regular starter):

• The next morning, weigh out 200 grams of your levain into a mixing bowl of your stand mixer. Then you can feed the rest as per your regular maintainance
• Add all the ingredients listed for the dough. Knead the dough with a dough hook until the dough is smooth and non-sticky (a bit tacky is fine but not sticky). You don't need to develop a window pane here. This takes about 10 minutes on speed 2 on Kitchen Aid. Proceed to the shaping step below

If using a stiff starter:

• About 8-10 hours before you plan to make the steamed buns, combine all ingredients for the stiff starter in a bowl. Stir a bit to roughly combine and then use your clean hand to knead it. This is a stiff starter, it's like dough. Make sure no pockets of dry flour are visible. Transfer to a large see-through container (plastic or glass is fine, preferably wide-mouth so you can get it out easier later). Loosely cover with the lid and let it ferment until triple in size

Prepare the dough using a stiff starter:

• Place all ingredients for the dough, including all of the stiff starter in a mixing bowl of a stand mixer fitted with a dough hook attachment. Use the hook to stir everything around a bit so when you turn the machine on, the flour won't fly around and wet ingredients won't splash (it happened to me before!). Start with the lowest speed to mix things up and then increase to speed 2 and knead for about 10 minutes or until it forms a dough that is smooth and not sticky. You don't need to knead until window pane stage. Proceed to the shaping step below

For round shape:

• Divide the dough into 8-10 equal portion and round them up into dough balls. Cover and rest the dough for 15 minutes. This is not to proof the dough. This is to relax the gluten for easier shaping
• Flatten and gather the edge to round them up into dough balls. Roll the dough into a smooth round ball in between the palm of your hand or as I did in the video. REALLY make sure the dough is smooth. Proceed to the proofing step

For mantou shape:

• Cover and rest the dough for 15 minutes. This is not to proof the dough. This is to relax the gluten for easier shaping
• Roll the dough into a long log and use a dough cutter to cut into 8-10 equal portions using a serrated knife is best so it won't squish the dough down. Lightly dab the surface of the bun with some milk using your finger to smooth the surface or mist with some water using a spray bottle. Proceed to the proofing step below

If you are going to make steamed buns with filling:

• Divide the dough into 10-12 equal portions. Flatten and gather the edge to round them up into dough balls. Cover and rest the dough for 15 minutes. This is not to proof the dough. This is to relax the gluten for easier shaping and rolling the dough
• Lightly dust the work surface with some flour. Work with one dough at a time. Flatten the dough with your palm and then use a rolling pin to roll it out to form a circle about 4-5 inches, with a slightly thicker middle part. This is to support the weight of the filling. Don't roll the dough too thin. If you roll the dough too thin, the filling might make the steamed buns "wrinkle" later when you steam. Place the filling at the center and then gather the sides to enclose the bun and pinch to seal. Flip the bun so the seam side is down now. Proceed to the proofing stage

Proofing:

• Let the dough rise at room temperature or at a warm place, about 86 F (30 C), don't go above this however. They won't necessarily double in size, but at least puff up to about 50% of the original size. If you are using a regular liquid starter, this may take about 4-5 hours or longer, depending on the strength of your starter
• If you use a stiff starter, the dough may be sufficiently proofed in about 3-3 1/2 hours at 86 F (30 C). Don't watch the time, watch the dough and test it to make sure they are sufficiently proofed
• How do you know if your buns have proofed ? They will be about 50% bigger than their original size AND when you lift them up, they should feel significantly lighter. If not, let them proof a bit longer. Use a finger test too. When you gently push on the dough, it will leave an indentation but it will spring back slowly. This dough is perfectly proofed. If it springs back right away, it needs to be proofed a bit longer. If it never springs back, then you have over-proofed the dough. Loosely cover them with plastic wrap and put the over-proofed buns in the fridge to slow down the proofing while waiting for the steamer
• An under proofed buns will be very dense and have bumpy surface after steaming. An over proofed buns may widen to the side and much flatter, but they shouldn't be dense and heavy. So, overproof may still be a bit "safer" compared to the buns not sufficiently proofed. Ideally, we want it to be perfectly proofed of course 

Steaming:

• Fill up the steamer with water but do not turn on the stove yet. Carefully arrange the proofed buns in the steamer, giving about 2 inches of space in between as they will expand quite a bit. Cover with a lid wrapped with a cloth to prevent condensation from dropping on the surface of the buns. If you use a bamboo steamer, you don't need to wrap the lid as bamboo steamer absorbs liquid
• Please note that I use the largest burner on my stove. Different sizes of burners will produce different amounts of heat, so use your largest burner. TURN THE HEAT TO MEDIUM (6/10)
• When the water comes to a simmer, crack the lid open about 1/2 inch gap and start the timer. Steam with the lid cracked open like that for 10 minutes
• After steaming, turn off the heat. DO NOT OPEN THE LID of the steamer. Let the buns sit there for 3 minutes. The buns will not sink or wrinkle due to the sudden change in temperature
• Proceed with the next batch and steam with the same method and setting as I mentioned above. You don't have to wait for the water in the steamer to cool down to start. Just turn on the stove to medium heat, crack the lid open immediately and the time starts when water is back to a simmer again

Serve warm:

• Serve them warm or immediately remove the buns to wire rack to let them cool down. This is to ensure the bottom of the steamed buns will not be wet and soggy

Storing:

• If you make extra and plan to store them, let the already steamed buns cooled down completely and then place them on a baking sheet, not touching each other, and then put the entire tray inside the freezer for about 1 hour. They will harden, but not completely frozen yet. Transfer to a freezer bag and they will not stick to each other anymore. Try not to keep for more than 1 month