Preheat your oven to 220°C (430°F). Gather a large baking sheet and a mixing bowl.
Peel and cut the carrots into evenly sized sticks, and trim the asparagus to about 4-5 inches in length. This ensures even roasting and beautiful caramelization.
In the mixing bowl, toss the carrots and asparagus with olive oil, making sure each piece is thoroughly coated. You should see a slight sheen and hear a gentle sizzle as the oil coats the vegetables.
Sprinkle generously with coarse sea salt and freshly ground black pepper. Add the smashed garlic cloves if using, distributing them evenly among the vegetables. Toss again to evenly season.
Spread the vegetables in a single layer on the baking sheet, making sure they aren’t overcrowded. This allows hot air to circulate and helps them develop crispy, caramelized edges.
Place the baking sheet in the oven and roast for 20-25 minutes. During this time, you'll notice the edges darken and turn a deep amber, and the aroma will fill your kitchen with warm, earthy scents.
Flip the vegetables halfway through with tongs or a spatula to ensure even browning on all sides. Keep an eye on them towards the end to prevent over-browning.
Once the vegetables are tender and nicely caramelized—carrots should be soft with crispy edges, and asparagus tips should be charred and crispy—remove the baking sheet from the oven.
Squeeze fresh lemon juice over the hot vegetables to brighten and balance the smoky sweetness. Toss gently to combine, then sprinkle with fresh herbs if desired.
Serve immediately while still warm, showcasing the crispy edges and smoky aroma. Enjoy this simple, flavorful side that elevates humble vegetables into a star dish.