Preheat oven to 425F. Line a baking sheet with a Silpat or spray with cooking spray; set aside.
Slice potatoes and put into a gallon-sized Ziplock.
Sprinkle cornstarch into bag, seal bag, and toss potatoes to coat.
Open bag and add oil, seal bag, and toss potatoes to coat.
Open bag and add smoked paprika, cumin, salt and pepper, seal bag, and toss potatoes to coat. Really manipulate the potatoes all around inside the bag, pushing the ones on the top to the bottom and vice versa, to equally distribute the oil and spices.
Transfer potatoes to baking tray, arranged in a single flat layer, not quite touching, if possible. They don’t have to be in rows, but I find this easiest when it’s time to flip.
Bake for about 25 minutes. Remove from oven, and with a tongs, flip potatoes over.
Return tray to oven and bake for about 15 to 20 more minutes, or until done.***
Remove from oven and serve as soon as they’re cool enough to eat; fries are best warm and fresh. Optionally, serve with ketchup or your favorite condiments.
*You may use another oil, like olive, vegetable, or canola. **You can substitute your favorite seasonings or seasoning blend, if desired. ***Baking times will vary based on your oven, the potatoes and how thick they’re cut, how full the tray is, and how well done you like your fries. Because it’s a very hot oven, keep a close eye on them in the final moments of baking so they don’t burn.