Place the sliced sweet potatoes in a large bowl with cold water.
Allow the sweet potatoes to soak in the water for an hour.
Preheat oven 450 degrees.
As the oven preheats place a baking pan in the oven for 6-8 minutes so that it becomes warm.
Drain the water from the bowl with the sweet potatoes. Dry the sweet potatoes with paper towels.
Place the sweet potatoes in a Ziploc bag with the corn starch.
Seal the bag and shake to evenly coat the fries.
Remove the heated pan from the oven. Line the pan with parchment paper and lightly spray with cooking oil spray.
Spread the fries onto the pan and coat them with the oil and seasonings. Make sure the fries do not touch.
Bake for 15-20 minutes.
Test the fries with a fork. If they are tender, flip them using a spatula.
Bake for another 5-10 minutes, or until they are tender-crisp.
Turn the oven off and leave the oven door open.
Keep the fries in the oven for about 5 additional minutes.