Combine either all savory or sweet topping ingredients in a bowl.
Peel sweet potatoes. Working with one potato at a time, cut a thin sliver lengthwise to keep potato flat on the work surface. Lay chopsticks on either side of potato. Cut potato cross-wise at 1/8 to ¼ inch intervals down to the chopsticks.
Preheat oven to 400°F. Place sweet potatoes on a baking tray. Brush with oil and roast for 40 minutes.
Remove sweet potatoes from oven and increase temperature to 425°F. Sprinkle with either sweet or savory topping over potatoes and return to oven for an additional 15 minutes.