There is a particular kind of quiet joy in pulling open a bamboo steamer and finding a tray of fat, glossy buns with a purple spiral running through them. These purple sweet potato steamed rolls — 双色紫薯馒头卷 in Chinese — are the sort of thing my mother would make on a slow Sunday, when the dough had time to relax and the kitchen smelled faintly of yeast and steamed sweet potato.
They are not difficult, but they are a dough project. You make one plain mantou dough, split it, tint half with purple sweet potato powder, then sandwich a soft mashed sweet potato filling between the two sheets before rolling it all into a log. The reward is a cross-section that looks like a cinnamon roll grew up in a Chinese kitchen. If you have ever made shaped steamed buns, you already have the muscle memory.
What Is 双色紫薯馒头卷?
馒头 (mántou) are the plain, unsweetened steamed buns of northern China — the everyday bread of the table. 卷 (juǎn) means “roll,” and 双色 (shuāng sè) means “two-colored.” So 双色紫薯馒头卷 is literally a two-color purple sweet potato mantou roll: a yeasted wheat dough rolled with a sweet potato filling, sliced, and steamed rather than baked.
Because there is no oven involved, the texture is entirely different from Western bread. Steamed buns are tender, moist, and slightly springy — closer to a soft milk bread than a crusty loaf.
Purple sweet potato (紫薯) is not the same as the orange-fleshed kind. It is drier, denser, and much less sweet, with a faint chestnut flavor. That is why I add a spoonful of condensed milk to the filling — it loosens the mash and gives it just enough sweetness to read as a treat without tipping into dessert territory.
Why This Recipe Works
- The dough is a simple 2:1 flour-to-water ratio, which is forgiving and easy to knead by hand.
- Lard (or a neutral substitute) shortens the gluten slightly, giving the buns that soft, snowy crumb.
- Splitting one dough and tinting only half means you get the two-tone effect without making two separate batches.
- Cold-water steaming — starting the buns in a cold steamer — gives the yeast a final gentle lift as the water comes to temperature.
- The three-minute rest after the heat is off prevents the buns from collapsing when the lid comes off.
Equipment Needed
- A bamboo or metal steamer with a lid (a 10-inch bamboo steamer fits 9 rolls comfortably)
- Parchment paper squares or a thin layer of cabbage leaves to line the steamer
- A rolling pin
- A large mixing bowl and a bench scraper or sharp knife
- A clean kitchen towel
- A digital scale (baking by weight really does matter here)
Ingredients
For the dough
- 300 g all-purpose flour (中筋面粉)
- 150 g water, room temperature
- 8 g lard (or vegetable shortening)
- 3 g instant yeast
- 2 g purple sweet potato powder (紫薯粉)
For the purple sweet potato filling
- 150 g steamed, peeled purple sweet potato
- 15 g condensed milk
Ingredient Notes
Flour: Chinese all-purpose flour (中筋面粉) sits around 10.5% protein. If you only have bread flour, cut it with a little cornstarch; if you only have cake flour, the buns will be too soft to hold their swirl.
Purple sweet potato powder: This is a dried, ground product sold in Chinese grocery stores and online. Do not substitute fresh mashed sweet potato in the dough — the extra moisture will throw off the hydration. If you cannot find the powder, you can leave the dough plain and rely on the filling alone for color, though you will lose the swirl contrast.
Condensed milk: A small amount goes a long way. If your sweet potato is very moist, start with 10 g and add more only if the mash feels dry. The filling should be spreadable but not runny.
Lard: Rendered pork lard gives the most traditional texture. Vegetable shortening or a mild neutral oil works, but the crumb will be slightly less tender. A note on storage: see my post on freezing fresh ingredients if you want to pre-portion the lard.
Prep & Mise en Place
Steam the sweet potato first — peel, cube, and steam for about 15 minutes until a chopstick slides through with no resistance. Mash it while still warm, then stir in the condensed milk. Set aside to cool to room temperature; a hot filling will tear the dough.
Weigh out everything else before you start. Once the dough is mixed, you will not want to be hunting for the yeast. Line your steamer with parchment squares now, too.
If your kitchen is cold, warm the water to about 30°C (86°F) before mixing. If it is hot and humid, room-temperature water is fine.
Cooking Process
Step 1: Mix and divide the dough
Combine the flour, water, lard, and yeast in a large bowl. Mix and knead until the dough is smooth and slightly tacky but not sticky — about 8 minutes by hand. Divide the dough in half. Add the purple sweet potato powder to one half and knead it in until the color is even. You now have one white dough and one purple dough.
Step 2: Roll out the dough sheets
Roll each piece of dough into a rectangle roughly 25 cm by 20 cm. Aim for even thickness — about 3 mm — so the roll does not bulge in the middle.
Step 3: Stack the sheets
Lay the white sheet on top of the purple sheet, pressing gently so they adhere. If the dough resists sticking, brush a little water on the surface first.
Step 4: Spread the sweet potato filling
Spread the mashed sweet potato and condensed milk mixture evenly across the top of the white sheet, leaving a 1 cm border on the far edge so the roll seals cleanly.
Step 5: Roll it up
Starting from the long edge closest to you, roll the dough into a tight log. Give it a few gentle rolls with your palms to even out the thickness — the log should be about 30 cm long.
Step 6: Slice into nine pieces
Using a sharp knife or bench scraper, cut the log into 9 equal pieces. Wipe the blade between cuts for cleaner edges.
Step 7: Arrange in the steamer
Place each roll cut-side up on a parchment square in the steamer basket, leaving about 3 cm between them for expansion.
Step 8: Proof until 1.5 times the size
Cover and let proof in a warm spot until the rolls have visibly puffed and are about 1.5 times their original size. Depending on your kitchen, this takes 40 to 70 minutes.
Step 9: Steam and rest
Press a roll lightly with a fingertip — it should spring back slowly. Place the steamer over cold water, bring to a boil, and steam for 15 minutes. Turn off the heat and let the buns rest, lid still on, for 3 minutes before opening. This prevents them from deflating.
Step 10: Serve
Lift the rolls out carefully — they are delicate when hot — and serve immediately. If you are planning a larger meal, these pair beautifully with something savory, like a silky seaweed egg drop soup or fish sauce cabbage.
Common Mistakes When Making Purple Sweet Potato Steamed Rolls
Overproofing. If the rolls puff to double or more, they will collapse the moment the lid comes off. Watch for 1.5 times, not “as big as possible.”
Wet filling. If your sweet potato mash is too loose, it will squeeze out during slicing. Mash it while warm so excess steam escapes, and add condensed milk gradually.
Rolling too thin. A sheet thinner than 3 mm will tear when you stack and roll. If it starts to fight back, let the dough rest for 10 minutes and try again.
Skipping the rest after steaming. The three-minute lid-on rest is not optional. The steam inside the basket is still equalizing, and opening early causes wrinkles and shrinkage.
Uneven slices. If your cuts are different sizes, the small ones will overcook while the big ones stay raw in the center. Use a bench scraper and measure if you have to.
Variations
You can swap the purple sweet potato for mashed taro (芋头) or kabocha squash, though both will need slightly different amounts of condensed milk. For a more savory version, skip the condensed milk entirely and add a pinch of salt to the mash.
If you want a stronger color, increase the purple sweet potato powder to 3 g. Any more than that and the dough starts to taste faintly of the powder itself.
Some cooks brush the rolled log with a thin layer of water before slicing, which helps the layers stay together. I have not found it necessary, but it works if your dough is on the drier side.
Frequently Asked Questions
Can I make these without purple sweet potato powder? Yes. Leave the dough plain and rely on the filling for color. The swirl will be less striking, but the flavor is nearly identical.
Why did my buns turn out yellow or gray? Purple sweet potato reacts with alkaline ingredients and can shift color. If your water is very alkaline, add a few drops of rice vinegar to the dough water.
Can I steam these in a metal steamer? Yes, but line the basket well — metal tends to create more condensation, which can leave soggy spots on the bottom of the buns. Wrap the lid in a towel to catch drips.
How do I know when the dough is kneaded enough? It should feel smooth and slightly elastic, and spring back when you press a finger into it. If it tears when you stretch it, keep kneading.
Can I use active dry yeast instead of instant? Yes. Proof it in the water with a pinch of sugar for 10 minutes first, then proceed as written. The proofing time may run slightly longer.
How to Serve
These are best eaten warm, straight from the steamer, with a cup of plain tea. They work as a breakfast, a snack, or a slightly sweet side to a savory meal. If you are serving them alongside a stir-fry, keep the rest of the meal on the lighter side — a simple blanched romaine lettuce or a bowl of rice is plenty.
For a heartier pairing, I like them next to savory pumpkin rice or a small plate of mung bean cakes for a snack table.
Storage & Reheat
Cool the rolls completely, then store in an airtight container at room temperature for up to one day, or in the fridge for up to three days. To reheat, steam them again for 5–6 minutes — the microwave works in a pinch but makes the crumb rubbery.
For longer storage, wrap each roll individually in plastic wrap and freeze for up to one month. Reheat from frozen in a steamer for 10–12 minutes.
Allergen Notice
This recipe contains wheat (gluten) and dairy (condensed milk). Lard is a rendered pork product, so it is not vegetarian — substitute vegetable shortening if needed. Always check the labels on your purple sweet potato powder and any packaged ingredients for cross-contamination warnings.
Nutrition Disclaimer
Nutrition information is estimated and provided for general guidance only. Actual values will vary based on the specific brands and quantities you use. This is not a medical or dietary recommendation.
About the Author & Recipe Development
I am Lin, and I grew up in my parents’ restaurant kitchen in Chengdu, where every dish on the menu had to earn its place. Steamed buns were the thing I learned first — not because they were easy, but because they were everywhere. This version came together over several test batches: the first was too sweet, the second too dry, and the third finally got the balance right. If you make it, I hope it earns a spot on your table too.
Authoritative References
- Classic Chinese steamed bun technique, as taught in northern Chinese home kitchens
- General food safety guidance on yeast dough proofing and steaming from the USDA
- Traditional mantou ratios documented in Chinese culinary textbooks
Purple Sweet Potato Steamed Rolls (双色紫薯馒头卷): Fluffy Swirled Buns
Equipment
- Bamboo or metal steamer
- Parchment paper squares
- Rolling Pin
- Large Mixing Bowl
- Bench scraper or sharp knife
- Clean kitchen towel
- Digital kitchen scale
Ingredients
Dough
- 300 g all-purpose flour 中筋面粉
- 150 g water room temperature
- 8 g lard or vegetable shortening
- 3 g instant yeast
- 2 g purple sweet potato powder 紫薯粉
Purple Sweet Potato Filling
- 150 g steamed peeled purple sweet potato mashed while warm
- 15 g condensed milk
Instructions
- Combine the flour, water, lard, and yeast in a large bowl. Knead until the dough is smooth and slightly tacky but not sticky, about 8 minutes by hand. Divide the dough in half. Add the purple sweet potato powder to one half and knead it in until the color is even. You now have one white dough and one purple dough.
- Roll each piece of dough into a rectangle roughly 25 cm by 20 cm, about 3 mm thick.
- Lay the white sheet on top of the purple sheet, pressing gently so they adhere. Brush a little water on the surface if needed.
- Spread the mashed sweet potato and condensed milk mixture evenly across the top of the white sheet, leaving a 1 cm border on the far edge.
- Starting from the long edge closest to you, roll the dough into a tight log. Give it a few gentle rolls with your palms to even out the thickness to about 30 cm long.
- Using a sharp knife or bench scraper, cut the log into 9 equal pieces. Wipe the blade between cuts for cleaner edges.
- Place each roll cut-side up on a parchment square in the steamer basket, leaving about 3 cm between them for expansion.
- Cover and let proof in a warm spot until the rolls have visibly puffed to about 1.5 times their original size, 40 to 70 minutes.
- Press a roll lightly — it should spring back slowly. Place the steamer over cold water, bring to a boil, and steam for 15 minutes. Turn off the heat and let the buns rest, lid still on, for 3 minutes before opening.
- Lift the rolls out carefully and serve immediately.
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