Lime cilantro sweet potatoes

• 2 lb sweet potatoes, peeled and cut into 3/4-inch pieces
• 3 tablespoons extra-virgin olive oil
• 3/4 teaspoon salt
• 1/4 teaspoon cayenne
• 1/2 teaspoon finely grated fresh lime zest
• 1 tablespoon fresh lime juice
• 1/4 cup chopped fresh cilantro

Put oven rack in lower third of oven and preheat oven to 425°F.
Toss sweet potatoes with 2 tablespoons oil and 1/4 teaspoon salt in a shallow baking pan. Arrange potatoes in 1 layer and roast, stirring halfway through roasting, until tender, about 25 minutes total. Stir together cayenne, zest, and remaining 1/2 teaspoon salt in a small bowl. Whisk together lime juice and remaining tablespoon oil in a medium bowl, then add potatoes. Sprinkle with cayenne mixture and cilantro, stirring gently to combine.