Place the cut potatoes in a large bowl and add the salt, pepper, chili powder, garlic powder, oil and cornstarch. You can mix the spices separately in a small bowl first then add them to the sweet potatoes.
1 teaspoon chili powder, 1 tsp garlic powder, ¼ tsp salt, ½ tsp ground black pepper, 1 tsp corn starch, 2 tbsp olive oil