Leaving the skin on both carrots and parsnips is a matter of personal preference. The skins of both vegetables are edible and contain nutrients and flavor. They can add a rustic, earthy flavor and provide additional texture. It is also convenient and saves time in preparation. Whereas, removing the skin results in a smoother and more uniform texture, as it removes any potential bitterness or toughness. If you decide to leave the skin on, make sure to wash the carrots and parsnips thoroughly to remove any dirt or debris.