Wash, peel if desired, and cut sweet potatoes and carrots into evenly sized chunks. Consistent sizing ensures even cooking and uniform caramelization.

Place vegetables in a large bowl and toss with olive oil, salt, and pepper. Add any optional spices or herbs at this stage and mix until evenly coated.

Spread the vegetables in a single layer on a lined baking sheet. Avoid overcrowding the pan, which causes steaming instead of roasting.

Roast in a hot oven, flipping halfway through, until the vegetables are tender inside and browned on the edges. The exterior should show visible caramelization without burning.

Taste and adjust seasoning. Add fresh herbs or a light drizzle of honey if desired, then serve warm.