Mac Mat Grilled Duck – Lang Son’s Signature Dish of the Tay and Nung People

Lang Son is a province rich in specialties – from khau nhuc (slow-braised pork belly) and egg rice rolls to sour pho – but when locals say “vịt quay Lạng Sơn” (Lang Son roasted duck), there’s no need for explanation. I tried it for the first time at Ky Lua Market on a cold winter morning when the mountain fog hadn’t yet lifted. The deep brown skin, glossy from layer upon layer of honey, and the quietly aromatic smell of mac mat rising from inside the cut duck – that combination is one of the clearest food memories I have from the Northeast.

— Kelly Thuy

What Is Mac Mat Grilled Duck?

Mac mat grilled duck is a whole duck that has been cleaned, cavity-stuffed with a mixture of fresh mac mat leaves and fruit combined with garlic, ginger, and seasoning, then sealed and coated in honey before being roasted over charcoal. The mac mat herb – a small tree in the citrus family native to Vietnam’s northeastern highlands – simultaneously eliminates the gamey smell common in duck and imparts a subtle, faintly tangy floral aroma that penetrates the meat as it roasts. No other grilled duck dish in Vietnam uses this combination.

Origins and History

Mac mat grilled duck is rooted in the daily food culture of the Tay and Nung people – the two largest ethnic minority groups in Lang Son province, who have inhabited this mountainous borderland for centuries. Both communities have long traditions of raising ducks along mountain streams and using foraged wild plants as seasonings. Mac mat, which grows naturally in the limestone forests surrounding their villages, was a familiar kitchen ingredient: used to de-odourise strong-smelling meats, add fragrance to soups, and season grilled dishes.

No historical record pinpoints exactly when the mac mat stuffing technique became established, but the practice has been passed down through generations of Tay and Nung households in Lang Son. The dish gained wider recognition as Lang Son’s border economy developed, particularly after the Dong Dang border gate and Ky Lua market resumed activity in the 1990s. Traders and visitors passing through began seeking out the duck as a local specialty, and it gradually became one of the dishes most strongly associated with the province.

What Is Mac Mat?

Mac mat (Clausena indica, family Rutaceae – the citrus family) is a small woody tree reaching 2–8 metres in height, growing wild and in cultivation across the limestone mountain provinces of Northeast Vietnam: Lang Son, Cao Bang, Bac Kan, and Quang Ninh. Its leaves are oval and glossy; when crushed, they release a distinctive aromatic oil – faintly citrusy, slightly tangy, with a mild resinous warmth that is wholly different from common kitchen herbs.

In Tay and Nung cooking, mac mat is used primarily as a de-odourising and flavouring agent for duck, pork, and freshwater fish. The volatile oils in the leaves are credited with masking the gamey or fishy smell while leaving a pleasant aromatic residue in the cooked meat.

Important: Mac mat is not the same as mac khen (mắc khén) – the Sichuan-type wild mountain pepper used in Tay Bac (Northwest Vietnam) cuisine. These are completely different plants with different aromas and culinary uses. The names look similar in romanisation but refer to two unrelated species.

That Khe Duck – The Authentic Base Ingredient

Not just any duck produces authentic mac mat grilled duck. The That Khe duck – a local free-range breed raised along the natural streams of That Khe town, Trang Dinh district, Lang Son – is considered the gold-standard ingredient for this dish.

That Khe ducks are raised with minimal confinement, foraging freely for shrimp, small fish, aquatic insects, and water plants along cold mountain streams. This natural diet and active lifestyle results in:

• Firm, lean meat that holds together during roasting rather than becoming soft or greasy
• Noticeably less gamey smell than commercially raised duck, reducing the need for heavy de-odourising
• More pronounced natural flavour that complements rather than competes with the mac mat aroma
• Typical live weight of around 2–2.5kg per bird at optimal roasting size

Ingredients

Core Ingredients (4–6 servings)

Equipment

Traditional Cooking Method

Step 1 – Clean the duck

Remove all feathers and organs. Rinse inside and outside with lightly salted water, then rub thoroughly with rice wine to neutralise any gamey smell – an important step even with That Khe duck, which is naturally milder. Pat completely dry with kitchen paper.

Step 2 – Prepare the mac mat stuffing

Wash mac mat leaves and fruit and pat dry. Roughly chop or bruise the leaves – avoid mincing them too finely, as keeping some texture allows the aromatic oils to release gradually during roasting rather than burning off too quickly. Combine with minced garlic, ginger, salt, and seasoning.

Step 3 – Stuff and coat with honey

Pack the mac mat mixture generously into the duck’s cavity. Seal the opening firmly with bamboo skewers or kitchen twine. Brush a thin, even layer of honey over the entire outer surface of the duck – neck, wings, back, breast. Allow to marinate for at least 30–60 minutes (or overnight in the refrigerator for deeper flavour penetration).

Step 4 – Roast over charcoal

Place on the spit or rack over medium charcoal heat – glowing red coals, no large flames, to prevent the honey glaze from burning before the meat cooks through. Roast for 60–90 minutes, rotating continuously for even cooking. Brush on additional thin layers of honey every 15–20 minutes. The duck is done when:

• The skin is a uniform deep mahogany brown and glossy – not black or patchy
• Juices run clear when the thickest part of the thigh is pierced
• The mac mat and honey aroma is clearly present in the steam

After asking several stall holders at Ky Lua Market, the consensus on the honey technique was consistent: brush in multiple thin layers, not one heavy coat. Each thin layer is allowed to dry before the next is applied. That’s what produces the deep, even mahogany colour rather than a patchy caramelised surface.

— Kelly Thuy, field notes, Lang Son

Flavour Profile

The most telling quality of a well-made mac mat grilled duck is the restraint of the mac mat itself. It doesn’t overpower the duck – it removes what shouldn’t be there (the gamey note) and adds what shouldn’t be named (an aromatic depth that you can’t quite identify but wouldn’t want removed). First-time diners often simply describe the duck as unusually fragrant without being able to locate the source.

How to Eat It

The duck is chopped into pieces immediately before serving. Eat it hot – the skin loses its delicate crispness as it cools, and the mac mat aroma is most vivid in the first minutes after carving.

The two classic ways to eat it in Lang Son:

• With duck noodle soup (phở vịt): Fresh rice noodles in clear duck-bone broth, topped with sliced roasted duck. The most common way it’s served at Lang Son restaurants and market stalls.
• With white sticky rice or steamed rice: Simpler, letting the duck speak for itself; dipped in fish sauce or soy sauce mixed with fresh ginger and chili.

The dipping sauce is intentionally understated: diluted fish sauce with shredded fresh ginger and sliced fresh chili is enough. The duck is the centrepiece – the sauce’s role is to provide a mild, savoury contrast, not to compete.

Side Dishes and Pairings

Price Reference

Where to Find Mac Mat Grilled Duck

In Lang Son

• Ky Lua Market (Lang Son city) – one of the oldest and most vibrant markets in the Northeast; multiple stalls sell freshly roasted duck from early morning, often selling out before noon.
• Lang Son Night Market (city centre) – evening market with duck stalls and duck noodle soup vendors.
• Le Loi and Ba Trieu streets (Lang Son city) – concentration of local specialty restaurants, most serving mac mat grilled duck on their regular menu.
• That Khe town, Trang Dinh district – the source of authentic That Khe duck; approximately 100km from Lang Son city, but worth the detour if you want the closest-to-origin experience.

Beyond Lang Son

• Hanoi – a small number of Northeast Vietnamese specialty restaurants serve mac mat grilled duck, though sourcing genuine That Khe duck at this distance is uncommon.
• Online – vacuum-packed mac mat grilled duck is available through Vietnamese e-commerce platforms (Shopee, Lazada, Tiki). Quality varies widely; choose sellers with verified reviews and cold-chain shipping.
• Cao Bang, Bac Kan – mac mat trees also grow in these neighbouring provinces, so local variants of the dish exist, typically made with regional free-range duck rather than That Khe duck.

Nutritional Value

The figures below are estimates based on the composition of the main ingredients (roasted free-range duck + honey glaze + mac mat herb). No independently verified laboratory nutritional analysis of mac mat grilled duck has been published. For clinical or dietary purposes, consult a registered dietitian.

Duck meat is rich in protein and iron but higher in fat than chicken, particularly in the skin. Those managing fat intake should remove the skin before eating. The mac mat herb contributes negligible nutritional value at the quantities used in a normal serving.

Storage Tips

• Eat immediately after carving for the best experience – the skin softens quickly as it cools.
• Leftovers: cool completely, wrap tightly, and refrigerate for up to 1–2 days. Reheat in an oven or dry pan at high heat for 3–5 minutes to restore some skin crispness – microwave reheating makes the skin rubbery.
• A whole roasted duck can be frozen for 2–4 weeks – quality drops noticeably compared to fresh but remains acceptable.
• Fresh mac mat leaves keep in the refrigerator for 3–5 days. They can be dried or pickled for longer storage, though the aromatic intensity reduces significantly.

Frequently Asked Questions About Mac Mat Grilled Duck

What is mac mat grilled duck?

Mac mat grilled duck (vịt nướng mắc mật) is a traditional specialty of the Tay and Nung ethnic people in Lang Son province, Northeast Vietnam. A whole free-range duck is stuffed with mac mat leaves and fruit, coated in honey, and roasted over charcoal to a deep mahogany colour and distinctive floral aroma.

What is mac mat?

Mac mat (Clausena indica, family Rutaceae) is a small tree native to the limestone mountain forests of Northeast Vietnam. Its leaves and fruit have a distinctive aromatic smell – faintly citrusy, slightly tangy – used to remove gamey odours from duck and pork while adding flavour. Not to be confused with mac khen, the unrelated mountain pepper from Northwest Vietnam.

What is That Khe duck and why does it matter?

That Khe duck is a local free-range breed raised along mountain streams in Trang Dinh district, Lang Son. Because these ducks forage freely for shrimp, fish, and aquatic plants, the meat is firmer, leaner, and less gamey than commercial duck – making it the preferred base for this dish.

What do you eat mac mat grilled duck with?

Most commonly with duck noodle soup (phở vịt) – fresh rice noodles in clear duck-bone broth topped with sliced roasted duck. Also eaten with white sticky rice or steamed rice, dipped in fish sauce or soy sauce mixed with fresh ginger and chili.

Is mac mat grilled duck the same as Lang Son roasted duck?

Yes – the two names refer to the same dish. “Lang Son roasted duck” is the informal shorthand; “mac mat grilled duck” specifies the defining ingredient. Many Lang Son restaurants use both names on their menus.

Can I substitute mac mat with another herb?

There is no perfect substitute. Kaffir lime leaves or Thai basil provide a partial approximation of the citrusy floral note. Dried or pickled mac mat, available from Vietnamese online stores, is a more faithful alternative when fresh mac mat is unavailable outside Vietnam.

Conclusion

Mac mat grilled duck is one of those dishes that exists because a specific community, a specific landscape, and a specific wild plant happened to come together in exactly the right way. The Tay and Nung people of Lang Son didn’t invent it as a showcase – they simply used what grew around them, refined the technique across generations, and produced something that can’t be authentically replicated once you leave the region.

If you’re travelling to Lang Son, go to Ky Lua Market early – the duck is at its best in the first hours after roasting, when the skin still has a whisper of crispness and the mac mat aroma is most present. A leg or thigh portion with a bowl of clear duck-bone pho is how the locals do it, and it’s hard to argue with.