Slice the sweet potatoes into long, thin strips, about 1/4-inch wide.
Add the fries to a large bowl and cover with cold water, soak for at least 60 minutes or even overnight for best results.
Preheat oven to 425 degrees F.
Line a large baking sheet with parchment paper and set it aside. You can also use two medium baking sheets, it is important for the fries to have enough room.
Drain well the fries, arrange them in one layer onto a clean towel and pat dry with paper towels. Clean the bowl in the meantime and dry it well.
Add the fries back to the clean bowl and drizzle with the olive oil, toss until evenly coated.
In a small bowl, whisk together the cornstarch, garlic powder, onion powder, dried parsley, smoked paprika, and black pepper until combined. Sprinkle the mixture on top of the fries, then toss until evenly coated and the cornstarch has soaked into the oil.
Spread the fries out in an even layer on the prepared baking sheet, making sure that the fries aren’t overlapping.
Bake for 15 minutes, remove the pan from the oven, and flip each fry with a spatula, making sure they are not overlapping. Bake for another 10-15 more minutes, or until the fries are crispy and have begun to brown a bit.
Once done, transfer the baking sheet to a cooling rack, sprinkle with your desired amount of sea salt, then let the fries rest for 5 minutes.