Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Peel and dice the sweet potato into 1/2-inch cubes, and chop the broccoli and bell pepper into bite-sized pieces.
Place the chicken breast in the center of the sheet pan and surround it with the prepared sweet potatoes, broccoli, and peppers.
In a small bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb mixture over the chicken and vegetables, using your hands or a spatula to toss the vegetables until evenly coated.
Roast in the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing it into strips to serve with the roasted vegetables.