Preheat oven to 425 degrees.
Bring a large stockpot of water to a boil. Place potatoes in pot and boil for about 6-8 minutes or until al dente. Don't let them cook too long here or they won't be firm enough to hold their shape.
Drain potatoes and then dry with paper towels. Make sure that they are very dry or they won't crisp up.
Mix the olive oil and spices in a medium to large bowl. Place potatoes in the mixture and toss to coat evenly.
For crispiness, spread sweet potatoes in a single layer on a baking sheet, lined with parchment paper if desired to prevent sticking. Use two baking sheets if necessary to prevent the potato strips from touching. (If the fries touch, the potatoes will steam instead of roast.)
Place potatoes in oven and bake for 30 minutes or until golden brown and crispy, turning them occasionally.
Remove from the oven and sprinkle with paprika, garlic powder, chili powder, or chopped fresh rosemary if desired. Serve with the chipotle dipping sauce or your favorite fry sauce.