Red Bean Buns (Dou Sha Bao): Steamed Recipe

i. Origin & history

Steamed wheat bread is the everyday staple of northern China. Plain buns are mántou (饅頭); filled ones are bāozi (包子), from bāo, 'to wrap'. Most baozi are savoury — pork, cabbage, mushroom — but the sweet ones form a family of their own: dòushā bāo with red bean paste, liánróng bāo with lotus seed paste, nǎihuáng bāo with custard, and sesame buns. Steamed buns have a long history in China, and the stories that connect mantou to the third-century strategist Zhuge Liang are traditional legends rather than history.

Dòushā (豆沙) means 'bean sand' — red bean paste — and is one of the oldest and most widespread sweet fillings in Chinese cooking. It is made from adzuki beans, the small red beans called hóngdòu in Chinese, cooked soft, sieved or blended smooth and then fried with sugar and oil or lard into a glossy, thick paste. The same paste fills mooncakes, sesame balls, tangyuan and pastries, and red beans are considered a warming, wholesome food.

The paste spread across East Asia. In Japan it became anko, the base of anpan, daifuku and taiyaki fish cakes; in Korea, pat fills bungeoppang and hoppang, Korea's steamed bun. Chinese dousha is typically richer than Japanese anko, because it is cooked with fat, which gives it a smoother, silkier texture and a darker sheen.

In southern China and Hong Kong, sweet buns are part of dim sum, though red bean buns are as much breakfast food as teahouse fare. Many are shaped with a pleated top or marked with a red dot so they can be told apart from savoury buns in the same steamer.

ii. How steamed buns stay smooth and white

A good red bean bun has a smooth, matt, almost porcelain skin and a cottony, even crumb. Three things produce it. The first is flour: lower-protein flour gives a softer, whiter bun than strong bread flour. Hong Kong bakers use a bleached, low-protein 'bao flour'; at home, plain flour, or plain mixed with a little cornflour, works well.

The second is kneading and shaping. Unlike bread, which only needs to be well developed, steamed bun dough needs to be kneaded until perfectly smooth, then rolled or pressed to push out large bubbles. Big air pockets left in the dough become blisters and craters on the surface after steaming. A short second rise after shaping — until the buns are about one and a half times their size, not doubled — keeps the crumb fine. Over-proved buns collapse and wrinkle as soon as the steamer is opened.

The third is steaming. Steam cooks at about 100°C, gently and with no crust, which is why the buns stay white. But condensation dripping from the lid leaves spots and pits, so cooks wrap the lid in a cloth or use a bamboo steamer, which absorbs moisture. A sudden temperature drop also makes the surface wrinkle: after the heat is turned off, the buns rest a few minutes with the lid on before it is lifted.

As for the filling, the oil in Chinese red bean paste is what keeps it smooth and soft once steamed. A dry paste firms up and pulls away from the bread; a paste fried with oil stays silky and moist in the centre of the bun.

iii. Ingredients

Makes 12 servings · scroll the side panel to adjust

200 g dried adzuki beans, soaked overnight
150 g sugar (filling)
50 ml neutral oil or melted lard (filling)
1 pinch of salt
400 g plain flour
40 g caster sugar (dough)
5 g instant yeast
1 tsp baking powder
210 ml lukewarm milk or water
15 g lard, butter or neutral oil (dough)

Use ready-made red bean paste (about 450 g) to save an hour; choose a smooth Chinese dousha or Japanese koshian. Homemade paste is much better and less sweet. Plain flour gives a soft bun; for very white, fluffy dim-sum-style buns, replace 50 g of it with cornflour or use Hong Kong bao flour. Baking powder alongside yeast gives a lighter crumb. Milk makes a richer, slightly sweeter bun; water gives the classic lean street-stall bun. Lard is traditional in both dough and filling; oil makes the buns vegan if you use water.

iv. Method

For the filling, drain the beans, cover with fresh water by 5 cm and simmer for 60–75 minutes, topping up, until they crush easily. Drain, reserving a little liquid, and blend to a smooth purée (sieve it for the finest paste).
Heat the oil in a non-stick wok, add the purée, sugar and salt, and cook over medium-low heat, stirring constantly, for 15–20 minutes until thick, glossy and it holds its shape on the spatula. Cool, then chill. Divide into 12 balls of about 35 g.
For the dough, mix the flour, sugar, yeast and baking powder. Add the milk and fat and knead for 10–12 minutes until very smooth and soft. Cover and leave somewhere warm for 45–60 minutes, until about doubled.
Knock back and knead for 2 minutes to remove large air bubbles. Roll into a log and cut into 12 equal pieces of about 55 g.
Roll each piece into a 10 cm round, thinner at the edges than in the middle. Place a ball of paste in the centre, gather the edges up and pinch firmly closed. Turn seam side down and cup gently into a smooth dome.
Set each bun on a square of baking paper in a bamboo steamer, 3 cm apart. Cover and prove for 15–25 minutes, until about one and a half times their size and light when touched.
Set the steamer over a wok of boiling water, wrap the lid in a cloth if it is metal, and steam over medium-high heat for 12–14 minutes.
Turn off the heat and leave the lid on for 5 minutes before opening, then serve warm.

v. Tips & common mistakes

Chill the filling. Cold paste balls are firm and easy to wrap; warm paste smears and stops the seam sealing.
Knead until smooth as silk. Lumpy or under-kneaded dough steams into a rough, pockmarked bun.
Don't over-prove after shaping. Over-risen buns look perfect in the steamer and collapse into wrinkles when the lid comes off.
Start with boiling water. Put the buns over water that is already at a full boil, so they set quickly and evenly.
Rest before lifting the lid. Five minutes off the heat prevents the sudden temperature drop that shrinks and puckers the skin.
Seal the seam well. A weak seam opens as the dough expands and the filling leaks onto the paper.

vi. Variations

Lotus seed buns (lianrong bao) use pale lotus paste and are often shaped like peaches for birthdays (shou tao bao). Custard buns (nai huang bao) and molten salted-egg liu sha bao are dim sum favourites. Twisted red bean rolls spread the paste over rolled dough and twist it into knots before steaming. Whole-bean filling (hongdou xian) leaves some beans whole for texture.

Baked rather than steamed, red bean paste fills Japanese anpan; wrapped in mochi it becomes daifuku or red bean mochi; and in Korea it fills the fish-shaped bungeoppang. For a firm, sliceable bean confection, see yokan.

vii. Serving & storage

Eat red bean buns warm from the steamer, for breakfast with soy milk or tea, or as an afternoon snack. At dim sum they come in small bamboo baskets of three.

Cooled buns keep for 2–3 days in an airtight bag in the fridge, though they firm up; re-steam for 5–8 minutes until soft and hot. They freeze very well for up to 2 months: freeze once cool, then steam from frozen for 12–15 minutes. The red bean paste keeps for a week in the fridge or 3 months frozen.

viii. Common questions

What is a red bean bun?

A red bean bun, or dou sha bao, is a soft Chinese steamed bun of yeasted wheat dough filled with sweet red bean paste made from adzuki beans. It is a common breakfast food and dim sum item across China.

What is red bean paste made of?

Adzuki beans cooked until soft, puréed and then cooked again with sugar and a little oil or lard until thick and glossy. Chinese versions usually include fat, which makes the paste smoother than Japanese anko.

Are red bean buns steamed or baked?

Chinese dou sha bao are steamed, which gives a soft, white, crustless bun. Baked red bean buns exist too, notably Japanese anpan and Chinese bakery buns, but they are made from an enriched bread dough with a golden crust.

Why did my steamed buns wrinkle?

Usually because they were over-proved, or the lid was lifted straight after steaming and the sudden temperature drop made the skin shrink. Prove only until one and a half times the size, and rest the buns in the closed steamer for 5 minutes off the heat.

Are red bean buns vegan?

They can be. Make the dough with water and oil instead of milk and lard, and use an oil-based red bean paste. Many street-stall buns are made this way, but check shop-bought ones for lard.

How do you reheat red bean buns?

Steam them for 5–8 minutes from the fridge or 12–15 minutes from frozen. A microwave works for one bun under a damp paper towel for about 30 seconds, but the texture turns chewy as it cools.