Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into bite-sized 1-inch cubes and slice the red bell pepper into thin strips.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken cubes, broccoli florets, and sliced bell peppers onto the prepared sheet pan.
Drizzle the lemon-herb oil mixture over the chicken and vegetables, then toss 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 18 to 22 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 extra fresh herbs if desired.