While the potatoes are roasting, prepare the toppings.
Lay flat on a baking sheet and roast 15 minutes, then flip each chip over. Continue roasting until crispy, about 25-30 minutes. (To get them even crispier, it can help to put them on an oven-proof cooling rack and place the rack on the baking sheet.)
Toss with oil and sprinkle with salt and pepper.
Once the potatoes have soaked, remove them from the water and dry well with a paper towel.
Preheat the oven to 425 degrees.
Place the slices in a large bowl and cover with warm water and corn starch. Allow to sit for 15-20 minutes. This step is very important because it removes the excess starches so the potatoes will get crispy in the oven. If you skip this step, you may have soggy sweet potato chips. Eeek!
Slice the sweet potatoes into very thin slices using a mandolin or very sharp kitchen knife.