To cut traditional fries: Slice the sweet potato (no need to peel) lengthwise into thin planks, about ¼- to ⅓-inch wide. Then cut each plank into similar width strips.
Add seasonings: Combine the garlic powder, salt, smoked paprika, and black or cayenne pepper in a small bowl and set aside. Toss the sweet potatoes with the oil to evenly coat, and then evenly sprinkle with the spice mixture and toss to coat.
To cook in the air fryer: Place the potatoes in an even layer in the air fryer basket and air fry at 400℉ for 10 to 12 minutes, tossing at the halfway point, or until tender on the inside and lightly golden on the outside. (Timing may vary slightly based on air fryer model and precise thickness of fries.)
Serve as is or with your favorite dipping sauce.
To roast in the oven: In this case, prepare the potatoes the same way. Then place a rack in the upper third to quarter of the oven and preheat the oven to 425℉. Place a rimmed baking sheet in the oven to get very hot, about 5 minutes. When hot, carefully place a sheet of parchment paper on top and then quickly distribute the prepared potatoes in an even layer. Roast in the upper portion of your oven for 12-15 minutes or until the potatoes are cooked through and lightly golden with some crisp edges. You may flip ¾ of the way through and place on a lower rack if the potatoes are browning too quickly—otherwise there is no need to flip. Precise cooking time will depend on oven, precise size of cut, and distance from the top element. Check a few minutes early and allow for an extra minute or two if needed.
Notes
Alternate spice mixture: For a hint of heat and Tex-Mex flavor based off my Spicy Sweet Potatoes recipe, I sometimes use ½ teaspoon each chili powder and kosher salt, ¼ teaspoon each cumin and smoked paprika, and ¼ teaspoon cayenne pepper (may use ⅛ t cayenne or sub fresh black pepper to taste for less heat). Try both and see if you have a favorite!Cooking tip: For even cooking and crispness, it's best to keep the fries in a single layer. That said, to fit a few extra in my air fryer, I often crisscross a few on top. In this case, I make sure all fries still have space around them and know that they may not be quite as crisp...but they still disappear fast!