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 bite-sized 1-inch cubes and chop the red bell pepper into similar sized pieces.
Place the chicken cubes, broccoli florets, and bell peppers onto the prepared sheet pan.
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, tossing thoroughly with your hands or tongs to ensure everything is evenly coated.
Spread the ingredients out in a single layer, ensuring they aren't overcrowded so they roast rather than steam.
Bake for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender and slightly charred at the edges.
Remove from the oven and serve immediately, optionally garnishing with fresh parsley or extra lemon zest.