Thick-Cut Sweet Potato Fries

From Cook's Illustrated | March/April 2014

Why this recipe works:

Despite their namesake, sweet potatoes have little in common with russet potatoes—arguably the ideal potato variety for making French fries. To compensate for sweet potatoes’ lack of sufficient starch, we coated thick-cut sweet potato wedges with a cornstarch slurry that quickly turned crispy… read more

Despite their namesake, sweet potatoes have little in common with russet potatoes—arguably the ideal potato variety for making French fries. To compensate for sweet potatoes’ lack of sufficient starch, we coated thick-cut sweet potato wedges with a cornstarch slurry that quickly turned crispy when fried. To ensure well-seasoned creamy, sweet interiors, we first treated the sweet potatoes to a blanch in water spiked with salt. Adding baking soda to the blanching water caused the potatoes’ exteriors to turn mushy and slough into the slurry, creating a more substantial, pleasingly orange crust. To limit sticking and cut down drastically on frying oil, we switched from frying in a Dutch oven to a 12-inch nonstick skillet. Finally (and optionally), we ditched commonplace supersweet ketchup in favor of an easy spicy, creamy fry sauce for serving.

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Serves 4 to 6

If your sweet potatoes are shorter than 4 inches in length, do not cut the wedges crosswise. We prefer peanut oil for frying, but vegetable oil may be used instead. Leftover frying oil may be saved for further use; strain the cooled oil into an airtight container and store it in a cool, dark place for up to one month or in the freezer for up to two months. We like these fries with our Spicy Fry Sauce (see related content), but they are also good served plain.

Ingredients

  • 1/2 cup cornstarch
  • Kosher salt
  • 1 teaspoon baking soda
  • 3 pounds sweet potatoes, peeled and cut into 3/4-inch-thick wedges, wedges cut in half crosswise
  • 3 cups peanut oil

Instructions

  1. 1. Adjust oven rack to middle position and heat oven to 200 degrees. Set wire rack in rimmed baking sheet. Whisk cornstarch and 1/2 cup cold water together in large bowl.

    2. Bring 2 quarts water, 1/4 cup salt, and baking soda to boil in Dutch oven. Add potatoes and return to boil. Reduce heat to simmer and cook until exteriors turn slightly mushy (centers will remain firm), 3 to 5 minutes. Whisk cornstarch slurry to recombine. Using wire skimmer or slotted spoon, transfer potatoes to bowl with slurry.

    3. Using rubber spatula, fold potatoes with slurry until slurry turns light orange, thickens to paste, and clings to potatoes.

    4. Heat oil in 12-inch nonstick skillet over high heat to 325 degrees. Using tongs, carefully add one third of potatoes to oil, making sure that potatoes aren’t touching one another. Fry until crispy and lightly browned, 7 to 10 minutes, using tongs to flip potatoes halfway through frying (adjust heat as necessary to maintain oil temperature between 280 and 300 degrees). Using wire skimmer or slotted spoon, transfer fries to prepared wire rack (fries that stick together can be separated with tongs or forks). Season with salt to taste and transfer to oven to keep warm. Return oil to 325 degrees and repeat in 2 more batches with remaining potatoes. Serve immediately.

Sweet Potato Fries Gone Wrong

The typical sweet potato fry is cut thin, which means too little creamy sweet potato interior. Cutting our fries into wedges was a good fix, but their shape wasn’t the only hurdle. Because sweet potatoes are low in starch—and a portion of what starches they do possess converts into sugars when heated—most sweet potato fries end up limp or burnt. Giving our sweet potato fries a starchy coating ensures a crust with a crispy texture.

LIMP, BURNT LOSERS: Low-starch sweet potatoes often burn before they crisp up.

KEY STEPS: MAKING GOOD ON SWEET POTATO FRIES

Here’s how we turned sweet potatoes into impressively crispy fries with perfect creamy interiors.

BLANCH: Blanching the wedges helps ensure that their interiors fully cook and turn creamy when fried. Adding baking soda to the water makes them tacky on the outside.

COAT: The cornstarch slurry stays put thanks in part to the parcooked wedges’ tacky exteriors, and it crisps up beautifully in the hot oil.

FRY: Frying the wedges in a nonstick skillet prevents them from sticking to the bottom of the pan. The change in vessel also allows us to use far less oil.

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