1
Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce.
Trim and halve Brussels sprouts lengthwise. Halve, peel, and cut onion into ½-inch-thick wedges; mince a few wedges until you have 1 TBSP (2 TBSP for 4 servings).
Toss Brussels sprouts and onion wedges on a baking sheet with a large drizzle of oil, salt, and pepper.
Roast on top rack until browned and tender, 15-20 minutes.