Prepare the potatoes: Using a mandoline slicer with the waffle grid attachment, slice the potatoes into waffle shapes. Alternatively, you can carefully slice them into thin rounds and then cross-hatch them with a knife to create the waffle pattern. Aim for slices about 1/8-inch thick.

Rinse and soak: Place the cut potatoes in a large bowl and cover them with cold water. Let them soak for at least 30 minutes (or up to 2 hours) to remove excess starch. This is crucial for crispiness. Drain the potatoes thoroughly and pat them completely dry with paper towels. Any moisture will cause the oil to splatter dangerously.

Prepare the seasoning: In a small bowl, whisk together the sea salt, granulated sugar, paprika, garlic powder, onion powder, and black pepper. Set aside.

Heat the oil: Pour the frying oil into a deep fryer or a heavy-bottomed pot. Heat the oil to 325°F (160°C) using a kitchen thermometer. It's important to maintain this temperature for optimal frying.

First fry: Carefully add a single layer of potato slices to the hot oil. Do not overcrowd the pot, as this will lower the oil temperature and result in soggy fries. Fry for about 3-4 minutes, until the fries are slightly softened but not yet browned. They should be pale and just cooked through. Remove the fries with a slotted spoon and drain them on a wire rack set over a baking sheet.

Second fry: Increase the oil temperature to 375°F (190°C). Once the oil reaches the correct temperature, carefully return the partially fried fries to the oil in batches. Fry for another 2-3 minutes, or until they are golden brown and crispy. Watch them closely to prevent burning.

Season and serve: Remove the crispy fries from the oil and immediately place them in a large bowl. Sprinkle generously with the prepared seasoning blend while they are still hot. Toss gently to coat evenly. Serve immediately while they are at their absolute best!