Preheat the oven to 425°F (220°C) and prepare a large baking sheet.
Place the sliced carrots on the baking sheet, drizzle with half of the olive oil, season with salt and pepper, and toss to coat evenly.
Roast the carrots for 10–15 minutes until slightly tender.
Remove the pan from the oven and add the asparagus. Drizzle with remaining olive oil and gently toss everything together.
Return to the oven and roast for another 10–12 minutes, until the carrots are fork-tender and the asparagus has lightly browned tips.
Taste and adjust seasoning. Finish with lemon juice or herbs if desired. Serve immediately.