To prepare the potatoes: wash and peel the potatoes. Cut them into thick wedges. (See Note 1 for cutting instructions). In a large bowl, soak the potatoes in cold water for at least 1 hour, or up to overnight!
To make the secret mixture: combine water and cornstarch in 1-cup measuring cup. Microwave for 1 minute or so, then mix it well until smooth, thick, opaque and gelatinous. Then stir in paprika and garlic powder. (I know, this sounds SO weird, but this's what really make these steak fries the best! I learned this trick from this America's Test Kitchen video and it was a game-changer!!!)
To cook the potato wedges: preheat the oven to 425°F. Spray 2 baking sheets with non-stick cooking spray and divide the oil between 2 baking sheets. Spread the oil evenly all over. (I use this pastry brush for this step.)
Drain the potato wedges and dry them well with paper towels. Coat the potatoes with the cornstarch mixture.
For oven method: arrange the potato wedges on the prepared baking sheets in single layer. And bake for about 30 minutes, or until cooked through, turning the fries half way through.
For air-fryer method: arrange the potato wedges in the basket in single layer. Spray olive oil over the potatoes. Cook for 15 minutes at 400°F, turning the potatoes half way though. (Make sure to spray olive oil after flipping the fries.) Depending on the size of your air-fryer, work in batches.
To serve, while the fries are fresh out of oven/air-fryer, sprinkle some kosher salt and ground black pepper to taste and toss to coat evenly.