Preheat broiler to high; line baking sheet with foil. Spray peppers with non-stick spray; place on baking sheet 4 inches below broiler. Roast until skins are blistered and black, about 15 minutes on one side and 5 minutes on the other side. Remove peppers to a bowl; cover with plastic wrap; set aside to cool.

Set oven to bake at 400°F.

In a mixing bowl, combine sweetpotatoes, olive oil, cumin, salt and half of the cilantro; mix well. Spread sweetpotatoes onto baking sheet; roast in oven until tender, about 30 minutes, stirring halfway through.

Meanwhile, peel peppers, cut off their stems and remove the seeds. Cut flesh into 1/2–inch squares.

Remove sweetpotatoes from oven, set aside until cool, about 10 minutes.

In a bowl, combine sweetpotatoes, peppers, beans, corn, onion, lime juice and remaining cilantro; toss gently. Serve warm or cold.