Toss sweet potatoes with 2 tablespoons oil and 1/4 teaspoon salt arrange potatoes in a single layer on a baking sheet lined with parchment paper. Roast, stirring halfway and cook until tender, about 25 minutes total.
While potatoes are roasting, mix together in a medium-sized bowl remaining 1 tablespoon oil, lime juice, chili powder, garlic powder, cayenne, lime zest, and remaining 1/4 teaspoon salt.
Add roasted potatoes to mixture and toss to incorporate . Top with cilantro and serve immediately.