Sweet potato balls — bite-sized balls of steamed sweet potato kneaded with tapioca starch and sugar, deep-fried and repeatedly pressed flat against the side of the wok so they spring back and puff up hollow. The shell turns crisp and golden, the inside chewy and airy. A cheap, addictive Taiwanese night-market snack, also sold as 'QQ balls'.
Sweet potato balls are a classic of Taiwan's night-market fried-snack carts. They grew out of the island's long reliance on the sweet potato — a cheap, abundant staple that Taiwanese cooks have turned into countless snacks. The trick that defines them is the wok-press technique: vendors press the frying balls again and again with a perforated ladle, and the dough's elasticity makes them rebound and inflate into hollow spheres. Sold by the scoop in paper bags, they are among the most affordable night-market treats, which is why young eaters nickname them 'QQ balls' for their springy, chewy bite.
Pop one whole into your mouth and the thin shell shatters with a quiet crackle, giving way to a hollow, chewy interior that pulls and stretches between the teeth. Faintly sweet from the sweet potato and the sugar, with a clean fried fragrance. Best straight from the cart, when the shell is still crisp and the inside warm and springy.
Sweet potato alone would fry into a dense lump; tapioca starch is what makes the ball hollow and chewy. Its long amylopectin chains gelatinize when fried and form a stretchy, elastic dough. The repeated pressing is the key step: each press compresses the ball and forces the steam inside outward; when released, the elastic shell springs back and the next burst of steam can no longer escape, so it inflates the ball from within. Frying at a moderate 160–180°C lets the inside cook through and stay airy before the shell over-browns; a final hotter burst crisps the surface.
Variations
The plain version is most common; some carts dust the balls with plum powder, seaweed powder, salt-and-pepper or sugar straight from the oil. Purple sweet potato or taro gives a different color and flavor, and some shops drizzle condensed milk or chocolate. The constant is the press-and-puff technique that makes them hollow.
On the Palate
Where Sweet Potato Balls sits in the Taiwanese flavor cloud
Ingredients
Serves 4How it's made
7 steps · 35 min active + 15 min waiting
- 120 min
Steam peeled sweet potato until very soft, then mash while hot.
- 28 min
Mix in sugar, then knead in tapioca starch a little at a time to a smooth, pliable dough that is not sticky.
Watch outKnead in the tapioca starch a little at a time only until the dough is smooth and pliable and no longer sticky — too much starch and the balls turn hard instead of chewy-hollow.
- 35 min
Rest the dough briefly, then roll it into small balls about 2 cm across.
- 46 min
Heat oil to a moderate 160°C and add the balls; fry until they float and the surface sets.
- 58 min
Once set, press each ball flat against the side of the wok with a perforated ladle and let it spring back; repeat the press several times as they fry.
Watch outOnce the balls have set, press each flat against the wok side and let it spring back, again and again — each press-and-release traps steam inside and inflates the hollow; skip it and they stay dense.
- 62 min
Raise the oil to about 180°C for a final minute to crisp and gild the shells.
- 71 min
Drain well; dust with plum powder, seaweed powder or sugar if liked and serve hot.
