Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel and dice the sweet potato into 1/2-inch cubes and place them on one side of the baking sheet.
Drizzle the sweet potatoes with 0.5 tbsp of olive oil and a pinch of sea salt, then roast for 10 minutes.
While potatoes roast, whisk together the remaining 0.5 tbsp olive oil, lemon juice, lemon zest, minced garlic, oregano, thyme, salt, and pepper in a small bowl.
Remove the baking sheet from the oven and add the chicken breast, broccoli florets, and sliced carrots to the open space.
Brush the lemon-herb marinade generously over the chicken breast and toss the vegetables to coat them evenly.
Return the pan to the oven and roast for 18-22 minutes until the chicken reaches an internal temperature of 165°F and the vegetables are tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy.