Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel the sweet potato, carrots, and parsnip, then chop them into uniform 1-inch chunks.
Spread the chopped root vegetables onto the baking sheet and drizzle with 1 tablespoon of olive oil.
Sprinkle the vegetables with half of the sea salt, black pepper, garlic powder, and onion powder, then toss to coat evenly.
Pat the turkey breast dry with paper towels and rub with the remaining tablespoon of olive oil.
Season the turkey breast on all sides with the remaining salt, pepper, garlic powder, and onion powder.
Clear a space in the center of the baking sheet and place the turkey breast there, nestling the vegetables around it.
Strip the fresh rosemary and thyme from their stems and sprinkle the herbs over the turkey and vegetables.
Roast in the center of the oven for 25 to 30 minutes, or until the turkey reaches an internal temperature of 165°F and the vegetables are tender.
Remove from the oven and let the turkey rest for 5 minutes before slicing into thick medallions to serve alongside the roasted vegetables.