Cut the potatoes into sticks (I like them between 1/4-1/2 inch wide and about 3 inches long).
Fill a bowl with filtered water and half and lemon. Add the potato slices in the water and let soak for 10 min. Remove and lay out on a clean kitchen towel or paper towels to dry. Once dry toss them with the oil.
Mix the spices, salt and pepper in a small bowl, and toss them with the sweet potatoes. Spread them out on 2 rimmed baking sheets.
Bake until brown and crisp on the bottom, about 15 minutes, then flip and cook until the other side is crisp, about 10 minutes. Serve hot.