1
Adjust racks to top and middle positions and preheat oven to 425 degrees. Wash and dry produce.
Cut potatoes into ½-inch-thick wedges. Halve, peel, and thinly slice onion. Mince a few slices until you have 2 TBSP (4 TBSP for 4 servings).
Trim and discard woody bottom ends from asparagus. (Save potatoes for another use.)