Wash the Chinese yam thoroughly. Wear gloves and peel the skin, then cut the yam into 3–5 cm chunks. Place the yam into a steamer with enough water underneath. Bring to a boil, then steam over medium heat for about 15 minutes, or until a chopstick can easily pass through the yam.

Remove the yam while hot, weigh out 220 g, and transfer it to a large bowl. Mash until smooth using a spoon or masher. Add 180 g water and mix well to loosen the purée, making it easier to incorporate into the dough.

Add the sugar and instant yeast to the yam purée. Add the flour and mix with chopsticks until no dry flour remains. Add the lard, then knead by hand until a dough forms.

Transfer the dough to a work surface and knead repeatedly until smooth and no longer sticky. This extra kneading helps create a fine, delicate crumb. There is no need for bulk fermentation at this stage.

Roll the dough into a large thin sheet, fold both ends toward the centre, then roll it out again. Repeat this rolling and folding process twice to smooth the dough and improve the final texture.

Roll the dough into a wide, thin sheet once more.

Lightly spray the surface with water to increase stickiness, then roll it tightly from one end into a log.

Cut the log in half.

Roll each half into a thinner, even rope, then cut into pieces about two fingers wide. Cut them slightly wider than the final size, as the dough will expand during proofing.

Place the shaped mantou onto steamer trays lined with steaming cloth, leaving space between each piece. Cover with plastic wrap or a damp cloth and proof in a warm environment (28–30°C) until doubled in size.

The dough is ready when gently pressed and it springs back quickly.

Bring plenty of water to a boil in the steamer. Once the water is actively steaming, place the trays inside, cover, and steam over medium heat for 12 minutes.

When finished, do not open the lid immediately. Let the mantou rest in the steamer for 3 minutes before uncovering to prevent shrinking or collapse.