1
Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 425 degrees. Wash and dry produce.
Dice sweet potato into ½-inch pieces. Halve, peel, and cut onion into ½-inch-thick wedges. Remove and discard any large stems from kale; chop into bite-size pieces. Strip rosemary leaves from stems; finely chop leaves until you have ½ tsp (1 tsp for 4).