Preheat oven to 425.
Peel sweet potatoes and cut into 1/4" fries.
Put sweet potatoes in Ziploc bag. Add corn starch, garlic powder and onion powder. Shake bag to mix together.
Line cookie sheet with parchment paper.
Lay out fries in a single layer on parchment paper. Make sure they aren't touching one another.
Cook for 30-40 minutes, turning over once half way through.
Remove from oven. Sprinkle with salt, paprika (optional) and cilantro (optional).