Bánh Rế: Southern Vietnam's Lattice-Fried Sweet Potato Snack

In the oil, sweet potato becomes a net

When you drop thin sweet potato into the frying pan, at first it looks like flimsy bits of thread. Then you spread it out a little with chopsticks, the bubbles in the oil turn fine, the edges move toward golden, and suddenly it becomes one sheet of lattice. Lift it onto a plate and while it is hot it sags a little, and after a few minutes the sound changes and it turns crisp. Bánh rế is a sweet where watching this change is part of the fun.

Bánh rế is a lattice-patterned fried sweet presented as a specialty of the area around Phan Thiet in Binh Thuan province, southern Vietnam. It is known locally as sweet potato or cassava shaved thin, coated in sugar and fried into thin discs. VietnamNet covers it as a sweet specialty of Phan Thiet, and a cultural site of Binh Thuan province features bánh rế as a simple sweet you meet while traveling.

What to protect when you make it at home is the fineness of the sweet potato and the oil temperature. Cut as thick as for candied sweet potato (daigaku imo), it won't form a lattice and will clump like a kakiage fritter. If the oil is too cool, the sugar and starch soak up oil and it turns heavy once cooled. If it is too hot, only the outside darkens and the moisture of the sweet potato stays inside. This article keeps the local backbone of "cut the potato fine and fry it sweet," and uses a small amount of rice flour and tapioca flour purely as support so it holds together in a home kitchen.

If you are making Vietnamese rice-flour dishes in a row, the difference is clear when you compare it with bánh bèo (in Japanese), also rice flour but steamed and eaten from small dishes. Bánh bèo gets its softness from steam; bánh rế sets its lattice with oil and sugar. Read on to bánh chưng (in Japanese), wrapped in leaves, and to bánh xèo (in Japanese), wrapped in herbs, and you will see how the word bánh in Vietnamese cooking takes in rice flour, glutinous rice, tubers and fried foods broadly.

Seen as a souvenir sweet of Phan Thiet

Phan Thiet is known as a seaside town, but in the context of souvenir sweets, besides fish sauce and seafood, simple sweets also come up. Bánh rế is often sold stacked in thin round shapes, and it is not a showy cream pastry but a sweet eaten for the aroma of sweet potato, oil and sugar. Its place is something you buy in a bag on a trip and nibble with tea at your lodging or on the way home.

It looks a bit like Japanese kakiage or imo kenpi (fried sweet potato sticks), but the eating is different. It is less a fritter where you eat the batter, and not as hard as imo kenpi one stick at a time. Thin sweet potato is joined here and there into a thin disc, so it breaks apart lightly when you crack it. The sweetness is definite, but not as deep as dark syrup; it is easiest to enjoy when the toasty aroma of fried sweet potato comes first.

If you try to carry the local method straight into a home kitchen, the type of potato and the way it is shredded make the difference. Some Vietnamese recipes and introductions mention cassava, but buying cassava every time isn't practical everywhere. So this article uses a sweet potato that is not too moist, shreds it fine, coats it in a thin batter and builds the lattice at an oil temperature of 165 to 170°C. Rice flour and tapioca flour are not the stars; they are only support to hold the shape in a home kitchen.

Ingredients (serves 4; makes 10 discs about 10 cm across)

This amount makes about 10 discs of bánh rế around 10 cm across. It serves 4 as a snack with tea, or 5–6 people as a light dessert. Don't put in too much at a time when frying; with a home skillet it is easier to shape them one at a time.

What is worth buying extra

What's worth shopping for here is the flour and oil temperature control. Sweet potatoes and sugar are fine from any supermarket, but a coarse flour makes the lattice heavy, and if you can't read the oil temperature the color changes from piece to piece. Rice flour, tapioca flour and a thermometer can all be reused if you go on to make more Vietnamese rice-flour dishes and fried sweets.

Tapioca flour is used not to make it chewy but to join the thin potato strands lightly. You can make it with potato starch, but tapioca flour gives a lighter bite once cooled.

If you aren't used to deep-frying, a thermometer is a flavor tool. Bánh rế changes color fast: below 165°C it soaks up oil, and near 180°C only the outside scorches easily.

Where it goes wrong

It turns greasy

The cause is one of the moisture in the sweet potato, the oil temperature, or the thickness. If moisture remains, the batter loosens and the bubbles turn rough the moment it enters the oil. If the oil is below 160°C, the surface soaks up oil before it sets. Spreading it thick keeps the moisture in the center and it feels heavy once cool. Wipe it dry, measure the temperature, and spread thin at 10–12 cm across, and it improves.

It won't hold a round shape

It breaks up if the potato is thick, the batter is scant, or you touch it too much right after it goes in. Cut the potato into 2–3 mm matchsticks and coat it so the batter is thin but covers everything. Once it's in the oil, don't move it much for the first 30 seconds; when the bubbles have set the surface a little, push the outer edge in with chopsticks. Pressing it flat closes the holes, so just tidying the outer edge is enough.

It scorches but is soft inside

The oil is too hot. At about 180°C the sugar colors first and only the surface turns brown before the moisture leaves the potato. Lower the heat and bring the oil back to around 165°C before putting in the next piece. Don't keep a scorched one, and remove small burnt bits from the oil with a skimmer so bitterness doesn't carry over.

The lattice is heavy and like a cracker

The batter is too thick or there is too much rice flour. The rice flour is only support for the shape, not the star. If thick white batter remains at the bottom of the bowl, add a little more sweet potato or dilute with 1–2 tsp water before frying the next one. It's right when you can see each strand of potato as you lift it with chopsticks.

Storage and reheating

Once completely cool, put them in a storage container with a desiccant and eat them at room temperature by the next day. On humid days they may soften a little within half a day even in a container. If you make them ahead, take out only the amount you'll eat that day on a plate and store the rest with paper between them, not stacked.

The sign it's ready to store is sound rather than looks. Right after frying it is quiet on the rack, but as it cools it gives a light dry sound when you pick it up. If you put it in the container before that sound appears, steam builds up in the container and it goes soft from the underside. On rainy days, after it's completely cool, dry it in a toaster oven at 120°C for just 1 minute, let it cool slightly and then store, and it softens less.

If it has gone soft, preheat the toaster oven to 160°C, lay foil on the tray and warm it for 2–3 minutes. It scorches easily, so keep watching and take it out as soon as the edges are light again. A microwave returns moisture and makes it softer, so it isn't suitable for reheating.

I don't recommend freezing. On thawing it absorbs moisture from the frost and the lattice turns heavy. If you do have leftovers, crush them lightly and put them on vanilla ice cream or yogurt: even without full crispness you still get the toasty aroma.

Pairing it at the table

Bánh rế is a sweet fried snack, so it suits being served a little at a time with warm tea better than being brought out in quantity after a meal. Drinks that lighten the mouth, such as green tea, roasted green tea, lotus tea or jasmine tea, go well. If you add fruit, sour ones such as mandarin, orange, pomelo or pineapple are easiest to enjoy.

If you build it into a Vietnamese menu, lean toward main dishes with little oil. After phở gà (in Japanese), the chicken noodle soup, bún chả (in Japanese), a light dish of herbs and rice noodles, or bún thịt nướng (in Japanese), with sweet-savory pork and rice noodles, you can create a flow by cracking and serving just one disc of bánh rế. If you serve it on the same day as the fried spring rolls chả giò (in Japanese), both use oil, so keep the amounts modest.

You can buy sweet potatoes the way you would for making candied sweet potato (daigaku imo). But where candied sweet potato is a dish coated in syrup, bánh rế is a sweet where you eat fineness and air. Aim for the texture of a thin lattice that cracks lightly, not a fluffy, mealy potato.

Frequently asked questions

Can I make it with cassava?

You can, but because the prep and availability are difficult in many home kitchens, this article recommends sweet potato. If you use cassava, use only cassava sold for eating, remove the peel and core, and follow the seller's prep instructions. For a first attempt, sweet potato is safer and less likely to fail.

Can I make it without rice flour?

Locally there are also versions centered on potato and sugar. But in a home kitchen the moisture and cut of the potato are hard to keep stable, so a small amount of rice flour makes it easier to form. If you leave out the rice flour, reduce the water in the batter by about 30 ml, just work the sugar thinly into the potato, and try it at a lower oil temperature.

Can I use potato starch in place of the tapioca flour?

Yes. If you use potato starch, reduce to 20 g. It gives a similar texture fresh from the oil, but once cooled it is a little harder and the flour shows more. If you are using it as help when rice flour alone breaks easily, tapioca flour holds together more lightly.

Can I make it in an air fryer or oven?

It won't turn out the same. Bánh rế is a sweet in which thin potato sets all at once in the oil, leaving gaps in the lattice. An oven or air fryer doesn't have enough oil, and the thin potato ends up closer to dry baked sweet potato chips. If you want to cut back on oil, think of it as a different dish, and fry it on the days you want the real bánh rế.

Which sweet potato is best?

A moderately starchy, drier sweet potato suits it better than a very moist, sticky honey-type one. If the potato weeps moisture when cut, wipe it well before using. If the potato is so dry it breaks when shredded, cut the soaking time to about 3 minutes before coating to prevent cracking.

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