Preheat your oven to 425 degrees Fahrenheit. Line a rimmed baking sheet with parchment paper. Peel the vegetables and cut the parsnips and sweet potatoes into 1-inch pieces. Cut the carrots into 1/2-inch discs.
1 pound carrots, 1 pound parsnips, 1 pound sweet potatoes
In a large bowl toss the vegetables with the olive oil, salt, and pepper.
3 tablespoons olive oil, 2 teaspoons kosher salt, 1/2 teaspoon black pepper
Spread the vegetables onto the parchment-lined baking sheet and bake for 15 minutes.
Remove from the oven, toss with the balsamic vinegar, and return to the oven for an additional 10 minutes.
3 tablespoons balsamic vinegar
Check the vegetables for tenderness. They should be easy to pierce with a fork. If this isn't the case at the end of the cooking time, add an additional 2 to 5 minutes.