Preheat oven to 425 F degrees.
Cut potatoes, somewhat evenly, into sticks.
In a small bowl, whisk together the olive oil, corn starch and salt.
On a rimmed baking sheet, toss the sweet potatoes fries with the corn starch mixture until evenly combined and spread on a single layer. Use 2 baking sheets if necessary. Crack freshly ground pepper over the fries.
Bake for 15 minutes, then flip the fries over with a spatula and bake for another 15, 25 minutes total, until the fries have developed a crispy exterior. Remove from the oven and sprinkle with flakey sea salt.