Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel and dice the sweet potato, carrots, and parsnips into uniform 1-inch cubes to ensure even roasting.
In a large mixing bowl, toss the vegetables with half of the olive oil, sea salt, and black pepper.
Spread the seasoned vegetables in a single layer on the prepared baking sheet, leaving space in the center for the turkey.
Mince the garlic and combine it in a small bowl with the remaining olive oil, dried rosemary, and dried thyme.
Pat the turkey breast dry with a paper towel and rub the herb-garlic oil mixture evenly over all sides.
Place the turkey breast in the center of the baking sheet, nestled among the root vegetables.
Roast for 25 to 30 minutes, or until the turkey reaches an internal temperature of 165°F and the vegetables are tender and golden brown.
Remove from the oven and let the turkey rest for 5 minutes before slicing into medallions.
Serve the sliced turkey alongside the roasted root vegetables for a complete, clean-eating meal.