Khanom Buang (ขนมเบื้อง)

The Street Sweet Thailand Folds in Half

ขนมเบื้อง is the two-part trick of Thailand's market stalls: a batter smeared so thin the shell shatters, and a sweet meringue that bakes and puffs the second it lands on the hot pan. Aroifin describes it as a dessert handed down from the grandparents' generation — one that many vendors have turned into a full-time trade — and TrueID notes that wherever you find a Thai market, a khanom buang stall is never far away. The classic topping is ฝอยทอง, the golden egg-yolk threads of Thai sweets, scattered over grated coconut.

The modern home version — the one Aroifin and Kapook (via Pantip member Diary Delicious) publish — builds the batter from rice flour and mung bean flour loosened with ice-cold water, a whole egg and palm sugar. But the older recipes insist on the crispness aids the quick version drops: Wongnai's ครูโย roasts and grinds whole mung beans at home, then kneads the flour with lime water, salt and a duck egg yolk; Pannipa's uses rice flour alone, sweetened with coconut sugar, and also works in น้ำปูนใส, the clear slaked-lime water that keeps the shell brittle.

The fillings then split the stall in two. The sweet half — foi thong and grated coconut — is universal. The savoury half has its own schools: Pannipa fries grated mature coconut in shrimp fat with salt and kaffir lime leaves until dry and loose, while ครูโย stir-fries chopped shrimp with garlic, pepper and grated coconut, and both finish with spring onion and sesame. Fold, rest on the rack, and eat warm.

The Recipe (home version, from Aroifin — the same batter Kapook's Pantip member uses)

The old-style batch (Wongnai, ครูโย): roast 300 g skinless mung beans, cool, grind fine and measure 2 cups; knead with 1 duck egg yolk, 2 tbsp lime water, 1 tbsp palm sugar, ¼ tsp salt and 1 tbsp plain flour; rest 20 minutes. Pannipa's โบราณ bowl: 200 g rice flour only, 200 g coconut sugar, 2–3 tbsp lime water, 150 ml water and 3 eggs — the yolks go into the batter, two of the whites into the cream. Her savoury filling fries 100 g finely grated mature coconut in 2 tbsp oil with shrimp fat and salt, plus 1–2 very finely sliced kaffir lime leaves, until dry and loose (see the disagreement below).

The Method

1. The batter. Mix the rice and mung bean flours, pour in the ice-cold water and whisk, then the egg and palm sugar — whisk or rub by hand until the sugar fully dissolves. Rest 15–30 minutes; it's Aroifin's rest that lets the shell set thin and crisp instead of tough.
2. The cream. Whip the egg whites with the icing sugar — fine sugar only, so it dissolves fast — and a few drops of lime juice, which brings the peaks up sooner. Stop at soft-to-firm peaks: firm enough to hold its shape, soft enough to stay tender when it bakes.
3. The pan. Medium-low heat, wiped with an oiled cloth — Pannipa's method, not pooled oil. Ladle the batter and smear it as thin as physically possible; the shell should be thinner than a crepe.
4. The fill. The moment the shell browns, smear on the cream — you'll see it cook and puff — then scatter the foi thong and grated coconut. Pannipa's warning stands: work fast, or the shell burns and turns bitter.
5. The fold. Fold in half with a spatula and lift onto a wire rack, not stacked while hot, so the steam escapes and the shell stays crisp. Eat warm.

Where Thai Sources Disagree

How Western Versions Get It Wrong

• Making a thick crepe. Khanom buang is smeared wafer-thin; the shell should crack, not fold like a pancake. A western crepe batter produces a soft, floppy pastry that is not khanom buang.
• Reaching for whipped cream or custard. The puffed sweet filling is beaten egg white and sugar — a meringue, nothing dairy. Recipes that reach for whipped cream, frosting or "marshmallow fluff" have swapped out the dish's engine.
• Deleting the meringue over raw-egg fear. Thai home cooks have an answer for exactly this: ครูโย whips hot syrup into the whites, which cooks them. You don't have to skip the meringue; you just have to heat it.
• Confusing it with the Vietnamese crepe. ขนมเบื้องญวน is a different dish — the Vietnamese savoury crepe — that happens to share the Thai word for "crepe". Aroifin keeps them in separate articles for a reason; they share a pan and nothing else.
• Skipping the crispness aids. Ice-cold water, resting the batter, and (in the old recipes) lime water are what keep the shell brittle. Skip them and the shell turns soft and chewy within minutes.

UK Ingredient Notes

• Rice flour and mung bean flour: both standard at East Asian grocers; mung bean flour is "moong flour" in South Asian shops. Don't substitute cornflour — it browns differently and the shell stays soft.
• Foi thong (ฝอยทอง): imported in jars at Thai grocers, or make it — egg yolks drizzled into sugar syrup until they set into golden threads.
• Palm sugar: solid blocks at Thai grocers. Shave it and dissolve it fully in the batter; lumps burn on the pan.
• Grated coconut: fresh or frozen grated coconut from Thai grocers. Desiccated coconut rehydrated in warm water works in a pinch — squeeze it dry first so the filling stays loose.
• Lime water (น้ำปูนใส): made from slaked lime or the red lime paste (ปูนแดง) sold at Thai grocers, stirred into water and decanted. The modern home batter skips it entirely, so you can too.
• Eggs: duck eggs for ครูโย's old-style batter at Chinese grocers; standard free-range eggs for the home version.

Sources

This recipe is translated from the following Thai-language sources. Where they disagree, we've said so.