Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast, sweet potato, carrots, and bell peppers into uniform 1-inch cubes to ensure even cooking.
In a small mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken and all the chopped vegetables into a large bowl and pour the lemon-herb dressing over them, tossing well to coat every piece.
Spread the mixture in a single layer across the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.