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I – Kelly Thuy – arrived in Lang Diem on a February morning, which is peak rau khuc season. The elderly residents told me no one knows exactly when banh khuc first appeared; they only know it was once considered a prestige dish – made exclusively for honoured guests or during the competitive folk-singing sessions between village Quan Ho groups. I bought a bag while the cakes were still warm from the steamer. Green skin with white glutinous rice grains stuck to the outside. One bite: elastic and soft, mild herbal note of rau khuc in the dough, smooth mung bean inside, fatty pork belly, then a hit of black pepper. A cake that needs nothing alongside it.
— Kelly Thuy
Lang Diem Village and the Quan Ho Connection
Làng Diềm, xã Hoà Long, TP Bắc Ninh không chỉ nổi tiếng là quê hương Thuỷ tổ Quan họ với làn điệu dân ca đằm thắm, trữ tình mà còn được du khách khắp nơi biết đến bởi món bánh khúc bình dị, thảo thơm của vùng quê Kinh Bắc.
Quan Ho Bac Ninh folk singing, recognised by UNESCO in 2009, is one of Vietnam’s most important musical traditions – an antiphonal singing practice between groups of male and female singers from different villages, carried out during spring festivals and community gatherings. Lang Diem (formal name: Viem Xa) is considered the Thuy To (founding) village of the Quan Ho tradition. In this cultural setting, banh khuc is not incidental. In the singing sessions between the Quan Ho groups of Lang Diem and the Quan Ho groups of other villages, banh khuc was brought out to offer guests.
The cake and the song share the same season, the same social context, and the same village. They grew up together.
Rau Khuc – A Wild Plant That Drives a Calendar
Rau khuc (Gnaphalium affine, Asian cudweed) is not cultivated. Nobody grows rau khuc – it quietly grows up by itself on the ploughed furrows and fertile alluvial flats. The plant emerges from the soil after the rice harvest (approximately the 10th lunar month) and grows through spring.
| Characteristic | Rau khuc (Gnaphalium affine) |
|---|---|
| Scientific name | Gnaphalium affine D. Don (family Asteraceae) |
| English name | Asian cudweed; Japanese cudweed |
| Growth season | 10th lunar month through 3rd–4th lunar month (approximately November–April) |
| Appearance | Low-growing; small, moist green leaves with a silvery sheen on the upper surface; distinctively mild herbal fragrance |
| Role in the cake | Provides the green colour and characteristic herbal aroma of the cake dough |
| Out-of-season substitute | Dried rau khuc – produces a brown-black cake; flavour preserved but colour lost |
The rau khuc season coincides precisely with the Lang Diem festival calendar: the 15th day of the 1st lunar month, the Vua Ba temple festival on the 6th of the 2nd lunar month, and the Well-Draining Festival on the 3rd of the 3rd lunar month. That is also the season of the rau khuc plant. These overlaps are not accidental – they are the deep seasonal logic of a food culture built over generations.
What Makes Lang Diem Banh Khuc Different
Ngoài đặc điểm là vỏ bánh khúc được làm từ gạo và rau khúc giống những nơi khác, điểm khác biệt của bánh khúc làng Diềm so với nơi khác là ở phần nhân bánh. And beyond the filling, the steaming technique creates something found nowhere else: the sticky rice shell.
| Banh khuc Lang Diem | Common banh khuc (Hanoi street style) | |
|---|---|---|
| Filling | Two distinct types: mung bean + pork belly, or pork-shallot-wood-ear mushroom with rau ram | Usually only simple mung bean |
| Dough technique | Parboiled before shaping (‘trung bot’) – develops characteristic elasticity | Usually no parboiling step |
| Steaming method | Bamboo steamer (chõ) with glutinous rice scattered between layers → creates sticky rice shell outside | Standard water-bath steaming, no sticky rice shell |
| Cultural context | Prestige dish for Quan Ho singing gatherings and village festivals | Street breakfast food |
Ingredients
| Ingredient | Quantity (12–15 cakes) | Notes |
|---|---|---|
| Non-glutinous rice | ~200g | Khang Dan or ‘203’ variety for the right elasticity. Soak 3–4 hours, grind fine, drain to correct moisture – not too dry (hard cakes) and not too wet (cakes fall apart) |
| Glutinous rice | ~100g | Soak 4–6 hours; kept whole; scattered between layers in the steamer to form the sticky rice shell – not mixed into the dough |
| Rau khuc (Asian cudweed) | ~150–200g fresh | In season: vivid green cake. Out of season: dried rau khuc gives brown-black cake, flavour intact |
| Hulled split mung beans | ~150g | Soaked, steamed until soft, pounded until completely smooth – shaped into a ball the size of a chicken egg |
| Pork belly | ~100g | Finely diced (mung bean filling) or minced (pork-shallot filling); sautéed with dried shallots, seasoned with fish sauce and pepper |
| Dried wood-ear mushrooms | ~20g | Soaked until soft, julienned – used in the pork-and-shallot filling variant |
| Dried shallots, black pepper, rau ram | To taste | Filling seasonings; the black pepper is important – it releases as a hit of warmth when biting into the cake |
| Banana leaves | A few leaves | Lines the steamer bottom and top; adds a faint fragrance to the cakes as they steam |
How to Make It
Step 1 – Make the rau khuc dough
Boil cleaned rau khuc until completely soft, then blend to a smooth paste, including the green cooking water. Mix into the drained rice flour and knead until the dough is uniformly green and pliable. If the dough is too dry, the cakes will be hard; if it’s too wet, they will fall apart. Form into small portions and parboil briefly in boiling water (the ‘trung bot’ step) – this cooks the outer surface of the dough, developing the elasticity that sets Lang Diem banh khuc apart from simply kneaded rice dough. Remove and cool.
Step 2 – Prepare the two fillings
Mung bean filling: Mung beans stripped of skins, soaked until soft, steamed until tender, pounded smooth, shaped into an egg-sized ball, with diced pork belly and a pinch of pepper for fragrance.
Pork and shallot filling: Dried shallots must be used, along with wood-ear mushrooms, black pepper, rau ram (Vietnamese coriander) and finely minced pork belly, all mixed together.
Step 3 – Shape the cakes
Take a portion of dough, form into a ball, flatten into a thin disc. Place filling in the centre. Wrap the dough around it completely – the skin must be thin, and the filling must not show through in any form. Shape into a round ball or the characteristic oval ‘cat’s ear’ (tai meo) or ‘elephant’s ear’ form.
Step 4 – Steam in the bamboo steamer (the defining technique)
Line a bamboo steamer (chõ) with banana leaves on the bottom. Arrange a layer of cakes. Scatter a thin, even coating of soaked glutinous rice over the top and sides of the cakes. Add more cakes, scatter more glutinous rice. Continue until the steamer is full. Seal with banana leaves on top, close the lid tightly and steam over steady heat for approximately 30 minutes.
Nobody boils banh khuc – they steam it in a chõ like steaming xoi. One layer of cake, then a thin scatter of soaked glutinous rice, just enough to stick evenly to the cake. As the cakes steam, the glutinous rice becomes tender and adheres to the green dough surface, forming a sticky-rice shell that distinguishes these cakes from every other kind.
Ba Them – who has been making banh khuc in Lang Diem for more than forty years – explained to me why water-bath steaming doesn’t work: “With water-bath steaming the cake cooks but there’s no sticky rice shell on the outside. With the chõ, the steam rises up and the glutinous rice cooks onto the cake. You hold it and it’s heavier, and when you eat it there’s the extra bui of the xoi. You can’t replace it.” The sticky rice shell is only possible with the right method – there is no shortcut.
— Kelly Thuy, field notes, Lang Diem village, Bac Ninh
Flavour and Texture
| Layer | Description | Source |
|---|---|---|
| Sticky rice outer shell | Slightly chewy and sticky before biting through; adds a layer of glutinous rice fragrance and texture outside the green dough | Soaked glutinous rice cooked onto the dough surface in the steamer |
| Rau khuc dough | Soft and elastic, mildly green in colour; a gentle herbal note that is present without being assertive | Non-glutinous rice flour + rau khuc puree |
| Mung bean paste | Smooth, slightly sweet, reminiscent of a very mild vegetable pâté; the neutral-sweet anchor of the filling | Mung bean pounded very smooth |
| Pork belly | Small fatty cubes that contribute richness and savouriness; the reason the cake is not too light | Diced pork belly sautéed with shallots |
| Black pepper | A distinct warmth that releases after biting; the flavour signal that this is a savoury cake and not a sweet one | Ground black pepper in the filling |
| Wood-ear mushroom (pork variant) | A light crunch within the soft filling; textural interest against the smooth mung bean | Julienned wood-ear mushroom |
The cake skin is glossy and chewy, harmonised with the fragrance of rau khuc, pepper, the nuttiness of mung bean, the pork and the crunch of wood-ear mushroom. No dipping sauce is needed – the filling is self-contained.
The Seasonal and Festival Calendar
Banh khuc Lang Diem is seasonal in two senses: the rau khuc plant and the spring festival calendar align completely.
People in Lang Diem only make banh khuc when honoured guests visit and on the occasions of the 15th day of the 1st lunar month, the Vua Ba temple festival on 6/2 (lunar) and the Well-Draining Festival on 3/3 (lunar). Those are also the seasons of the rau khuc plant.
This means the cake’s cultural peak is also its botanical peak: the best green rau khuc, the freshest spring morning, the Quan Ho singing season, the village festival. All of them in the same window. Outside this period, the village makes banh khuc with dried rau khuc – the brown-black cake that still tastes of the tradition even when the colour is gone.
Where to Find It
At Lang Diem village
- Viem Xa hamlet, Hoa Long commune, Bac Ninh City – The primary and most authentic source. Well-known craft makers include Ba Them, Ba Vien and Co Hiep. Morning purchase is recommended – fresh-steamed cakes are best eaten immediately.
- Bac Ninh City markets – Stalls specialising in local specialties sometimes carry Lang Diem banh khuc; ask specifically for the village origin.
From Hanoi
Bac Ninh City is approximately 30km from central Hanoi – roughly 40–50 minutes by car or motorbike. A practical half-day trip, often combined with visits to the Quan Ho cultural sites: the Vua Ba temple, the Lang Diem communal house (dinh), and the spring festivals if visiting in February–March.
Price Reference
| Context | Approximate price (VND) | Notes |
|---|---|---|
| Direct from craft makers in Lang Diem | ~5,000–10,000 per cake | Usually sold in bags of 5–10 cakes; eat immediately while warm |
| Bac Ninh City market stalls | ~8,000–15,000 per cake | Slightly higher; verify Lang Diem provenance |
Nutritional Value
Estimated based on primary ingredients. No independently verified nutritional analysis of banh khuc Lang Diem has been published.
| Nutrient | Estimated value / 2–3 cakes (~150–180g) |
|---|---|
| Energy | ~250–320 kcal |
| Carbohydrates | ~45–55g (non-glutinous rice + glutinous rice coating) |
| Protein | ~8–12g (mung bean + pork belly) |
| Total fat | ~8–12g (from pork belly) |
| From rau khuc | Mild dietary fibre and polyphenol contribution; primary role is flavour and colour |
| From mung bean | Plant protein, dietary fibre, B vitamins, potassium |
Frequently Asked Questions
What is banh khuc Lang Diem?
A traditional Vietnamese rice cake from Lang Diem village (Quan Ho folk singing birthplace), Bac Ninh. Non-glutinous rice flour mixed with boiled rau khuc (Asian cudweed), filled with smooth mung bean paste and diced pork belly or a pork-shallot-wood-ear filling, steamed in a bamboo steamer with glutinous rice scattered between layers to form a sticky rice shell outside. Eaten hot immediately after steaming.
What is rau khuc?
Asian cudweed (Gnaphalium affine, family Asteraceae) – a wild plant that grows in northern Vietnamese paddy fields from November through April without cultivation. Small green leaves with a silvery surface sheen and a distinctive mild herbal fragrance. In the cake, it provides the green colour and gentle herbal aroma of the dough. Tiếng Việt: rau khúc.
What makes this different from other banh khuc?
The two-filling system (mung bean variant and pork-shallot variant), the parboiling step for the dough (trung bot technique), and the bamboo steamer method with glutinous rice scattered between cake layers – which produces a sticky rice shell outside each cake. This last technique is specific to Lang Diem.
Why is it connected to Quan Ho folk singing?
Lang Diem is the acknowledged founding village of Quan Ho Bac Ninh folk singing (UNESCO Intangible Cultural Heritage, 2009). Historically, banh khuc was prepared to serve honoured guests and to offer during the competitive inter-village singing sessions. The cake and the folk tradition share the same seasonal peak (spring), the same social context (village festivals and gatherings) and the same village.
When is the best time to visit?
January–April (solar calendar) for fresh green rau khuc and peak festival season. The Vua Ba temple festival (6th of 2nd lunar month) and the Well-Draining Festival (3rd of 3rd lunar month) are the two most significant occasions when banh khuc is most actively made and consumed at the village.
Conclusion
Banh khuc Lang Diem is not impressive because of exotic ingredients or elaborate technique. What makes it worth understanding is the alignment: a wild plant that only grows in spring, a steaming method that only works in a bamboo steamer, a village that is also the birthplace of a UNESCO folk singing tradition, and a calendar that brings all of them together in the same weeks each year.
Go to Bac Ninh in February. Take the road to Viem Xa. Find Ba Them or Co Hiep’s house. Buy a bag of cakes that are still warm from the steamer and eat them on the spot, in the village, before they cool. That is the full version of what banh khuc Lang Diem is.
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