Arrange oven racks to the upper level of your oven.
Place sweet potatoes in a large bowl and cover with cold water. Allow them to soak for just over 1 hour.
When ready to bake, preheat oven to 450°F (230°C). Lighlty grease 2 baking sheets with nonstick cooking oil spray or brushed with oil. Place baking sheets into the oven to preheat.
Drain wedges and pat dry with paper towels as much as you can to get as much moisture out as possible.
Spoon corn starch into a large zip-lock (or plastic) bag. Add the wedges; seal the bag with air in it and shake vigorously to evenly coat.
Using tongs, transfer coated wedges into a large bowl, shaking off the excess starch. Drizzle wedges with the oil and seasonings (DO NOT ADD SALT). Toss well to evenly coat.
Carefully remove pre-heated oven trays from the oven and arrange wedges in a single layer with plenty of space between them (at least 1/2-inch or 1cm gaps).
Bake for 15-20 minutes. Remove trays from the oven and test wedges with a fork. If they are just tender; flip them into a single layer again with plenty of space between them. Return wedges to the oven and bake for a further 5-10 minutes, until tender-crisp.
Turn oven heat off oven and leave oven door ajar allowing the wedges to dry out slightly and crisp up in the oven for about 5 minutes extra before serving. Prepare your Aioli dip.