A steamed bun is a soft, pillowy bread cooked over boiling water instead of in a dry oven. Originating in China over 2,000 years ago, steamed buns come in two broad categories: plain, unfilled buns called mantou, and filled buns called baozi (often shortened to “bao”). Today they’re a staple across East and Southeast Asia, with dozens of regional variations stuffed with everything from barbecue pork to sweet custard.
Mantou vs. Baozi: The Two Main Types
The simplest steamed bun is mantou, a plain white bun with no filling. It’s the Chinese equivalent of a dinner roll, eaten alongside soups, stews, or braised dishes to soak up sauce. Mantou has a slightly sweet, neutral flavor and a dense, springy chew. Some versions are lightly sweetened with sugar or enriched with milk.
Baozi refers to any steamed bun with a filling sealed inside. The dough is rolled into a disc, filled, then pinched closed with characteristic pleats on top. Fillings vary enormously by region. In southern China, char siu bao (barbecue pork buns) are a staple of dim sum restaurants, filled with diced roast pork in a sweet, sticky sauce. Northern Chinese baozi tend toward savory ground pork and cabbage. Sweet versions might contain red bean paste, lotus seed paste, or custard.
In everyday Chinese, both words have blurred over time. In some northern regions, “mantou” can refer to any steamed bun, filled or not. But in most contexts, mantou means plain and baozi means filled.
Steamed Buns Across Asia
China isn’t the only country with a steamed bun tradition. In Japan, filled steamed buns are called nikuman (literally “meat bun”), typically stuffed with seasoned ground pork and sold as hot street food at convenience stores. Vietnamese bánh bao are larger and often include a hard-boiled quail egg and Chinese sausage alongside the pork filling.
Taiwan is known for gua bao, a folded steamed bun shaped like a taco. The bun originates from the Fujian province of China but is most closely associated with Taiwanese street food. The classic filling is braised pork belly with pickled mustard greens, cilantro, and crushed peanuts. This folded shape, sometimes called a lotus leaf bun, has become wildly popular internationally, showing up on restaurant menus from London to Los Angeles with creative fillings like fried chicken or crispy tofu.
What Makes the Dough Different From Bread
Steamed bun dough starts with many of the same ingredients as bread: flour, water, yeast, and a pinch of sugar. The key difference is the cooking method. Baking in a dry oven creates a firm crust through browning reactions that only happen at high temperatures. Steaming surrounds the dough with 100 percent humidity at around 212°F (100°C), so no crust forms. The surface stays soft, smooth, and white.
The flour matters too. Standard steamed buns use medium-gluten flour with a protein content around 11 to 12 percent, similar to all-purpose flour. This produces a tender crumb without the strong chew of artisan bread, which typically uses higher-protein bread flour. During steaming, the starch in the flour absorbs moisture and gelatinizes, giving the bun its characteristic springy, almost marshmallow-like bounce.
Many recipes also include a small amount of baking powder alongside the yeast. The yeast handles the primary rise through fermentation, producing carbon dioxide over an hour or two of proofing. The baking powder acts as insurance, releasing additional gas once the bun hits the steam, which helps create an extra-light, airy texture. This combination of biological and chemical leavening is one reason steamed buns feel softer than most Western breads.
How Steamed Buns Are Cooked
The traditional cooking vessel is a bamboo steamer basket stacked over a wok of boiling water. The bamboo absorbs excess moisture, preventing condensation from dripping onto the buns and leaving wet spots. Each bun sits on a small square of parchment paper to keep it from sticking. Stacking multiple tiers lets you cook a large batch at once.
Cooking time is short compared to baking. Most steamed buns are done in 12 to 18 minutes, depending on size. Larger filled buns like char siu bao take closer to 20 minutes. The buns puff up visibly during steaming, and the dough turns from slightly translucent to bright, opaque white when finished. Opening the steamer too quickly can cause them to deflate or wrinkle, so most recipes recommend cracking the lid slightly for a minute before fully removing it.
Nutrition and Storage
A plain mantou (roughly 100 grams) contains about 230 to 250 calories, mostly from carbohydrates. The estimated glycemic index of a wheat steamed bun is around 70, essentially the same as white baked bread. Filled buns vary widely depending on what’s inside: a pork baozi will add protein and fat, while a red bean paste bun adds sugar.
Steamed buns freeze exceptionally well, which is one reason they’ve become a global convenience food. Commercially frozen steamed buns stored at minus 18°C (0°F) or lower keep for six months or longer. To reheat, you simply steam them again for a few minutes, or microwave them under a damp paper towel. The texture stays remarkably close to fresh, which isn’t always true of baked breads after freezing.
A Long History Behind a Simple Food
Steamed buns trace back to at least the third century BCE in China, during the Qin dynasty. They became widely popular during the Han dynasty (206 BCE to 220 CE), when wheat-based foods like noodles and flatbreads spread across the country. The first written reference to “mantou” by that name appeared around 300 CE.
The most famous origin story is almost certainly legend, but it’s too good not to mention. During the Three Kingdoms period, the military strategist Zhuge Liang was returning from a campaign in the south and encountered a river too rough to cross. Local custom called for human heads to be thrown into the water to appease the river spirits. Zhuge Liang refused, and instead ordered his men to slaughter livestock, stuff the meat into buns shaped like human heads, and toss those in. The river calmed, and the buns were named “mántóu,” a word that originally sounded like “barbarian’s head.” The name stuck, even as the meaning faded. Today, mantou are simply one of the most common everyday foods in China, eaten at breakfast, lunch, and dinner by hundreds of millions of people.