I don’t think I’ve ever enjoyed an oven-baked sweet potato fry. Despite their—and our—best efforts, potatoes cut thinly, tossed in oil, and roasted in a screaming-hot oven, often emerge dry and leathery, hard but not crisp. And yes, there’s the par-boiled then hard-roasted fries, but those, at their best, taste like, well, roasted sweet potatoes.
So I retraced. For a fry to be truly called a “fry,” shouldn’t we be frying? But, sure enough, there’s a reason sweet potato fries are often made in the oven: Dropping sweet potatoes—which contain more sugar, more water, and less starch than regular potatoes—in hot oil will yield fries that burn before ever becoming crisp. Bear with me as we talk fry-ence.
I turned to food science–wizard (and Serious Eats and New York Times contributor) Kenji J. López-Alt’s fry guide for answers: He adds vinegar to his fry blanching water. Vinegar, he says, slows the breakdown of pectin present in potatoes. So how about we slow it—and the resulting Maillard reaction—even more? I added double the amount of vinegar he recommends to the blanching water, along with salt (why not season the fry’s interior while we’re here?). Tossing the blanched fries in a cornstarch slurry ups the starch that sweet potatoes naturally lack, creating a barrier that’s eager to crisp.
The result? Sweet potato fries that are tender, not dry nor hollow, and so very crispy. There was not a leathery, chewy, nor hard one in the batch. And, the fries actually tasted of sweet potato—not fry oil—thanks to that seasoned blanching water. Hit these with more seasoning if you want—like cinnamon sugar, kale-pecorino dust, or zab-zab. But they really are so good on their own—you might not even need ketchup. —Coral Lee
- Prep time 2 minutes
- Cook time 30 minutes
- Serves 2
medium sweet potato (about 1/2 pound), unpeeled, cut to 1/4-inch matchsticks
kosher salt, plus more for finishing
frying oil, such as canola, vegetable, or peanut
- Whisk the cornstarch with 2 tablespoons of water in a large mixing bowl until smooth. Set aside.
- Combine the potato, vinegar, ¾ teaspoon salt, and 2 cups of water in a small saucepan. Bring to a boil over high heat, then reduce the heat and simmer for 10 minutes, or until tender but not falling apart. Using a slotted spoon or spider, lift the potatoes out of the water, tapping a few times to drip dry, then transfer to the bowl of cornstarch slurry. Toss to coat well, taking care not to break our (strong, but tender!) fries.
- Pour the oil into a medium stock pot fitted with a frying thermometer, and set over high heat. Also heat the oven to 200°F—this is where we’ll be keeping our fries warm.
- Once the oil reaches 325°F, drop in a third of the fries. Fry for 8 minutes at 325°F, agitating with a pair of tongs or cooking chopsticks to prevent large clumps from forming, and dropping or raising the heat as needed. Lift fries out with the same slotted spoon or spider, and transfer to a towel-lined baking sheet. Season with salt, and keep warm in the oven as you repeat with the remaining two batches.
- If you don’t have a thermometer, you can test the oil by dropping in a fry—if and when the oil bubbles fiercely, like froth, around the fry, you’re good to go. I found that to keep the oil at 325°F required maintaining high heat for the first 5-6 minutes of frying, then dropping the heat to medium-low for the last 1-2 minutes of frying.