Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and cut it into 1/2-inch cubes, then slice the red bell pepper into thin strips.
Cut the chicken breast into uniform 1-inch bite-sized pieces to ensure even cooking and quick roasting.
In a large mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken, sweet potato cubes, broccoli florets, and bell pepper strips to the bowl, tossing thoroughly until everything is well-coated in the marinade.
Spread the mixture in a single layer across the prepared sheet pan, ensuring pieces are not overcrowded so they roast rather than steam.
Bake for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.