Soak the cut sweet potatoes in cold water for an hour (I do overnight).
Preheat the oven to 400 degrees.
Dry the sweet potatoes well with paper towels then add to a ziploc bag with cornstarch.
Toss the potatoes with the cornstarch really well, then add in the canola oil and make sure its all coated.
Add them in a single, non touching, layer to your cookie sheet and roast for 15 minutes.
Flip the potatoes then spray the sweet potatoes with 1 second of canola oil spray.
Roast for an additional 15 minutes before serving.
Garnish with salt just before serving.