Preheat oven to 425 F/220 C. In a large bowl, whisk the vegetable oil with the orange juice, salt and pepper. Peel and cut the sweet potatoes into ½-inch/1 cm thick strips. Toss the sweet potatoes with the vegetable oil mixture until well coated.
Place potatoes in a single layer on a large baking sheet. Bake until tender, about 15-20 minutes, tossing halfway during the cooking time.
Combine brown sugar with cinnamon, if using, chili powder and paprika. Sprinkle evenly over sweet potatoes. Bake until glazed, about 5-10 minutes.
Tip: If one of your family members is sensitive to spices, they can be omitted. Just add brown sugar alone at the end and follow the same baking time to glaze sweet potatoes.