Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized cubes and chop the broccoli and bell peppers into similar sized pieces.
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, broccoli, and sliced bell peppers onto the prepared sheet pan.
Drizzle the lemon-herb marinade over the ingredients and toss thoroughly with your hands or tongs to ensure everything is evenly coated.
Spread the mixture out into a single layer, ensuring the chicken pieces are not crowded so they brown properly.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender-crisp.