Lemon and dill are the perfect compliment to the sweet, grassy flavor of asparagus. Roasting asparagus intensifies its sweetness.
Preheat oven to 350 degrees. On a rimmed baking sheet, toss asparagus with olive oil; season with salt and pepper. Roast until tender and browned in spots, 20 minutes. Toss with red-pepper flakes, dill and lemon zest.