Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Chop the red bell pepper and zucchini into bite-sized pieces, and break the broccoli into small florets.
Slice the chicken breast into even 1-inch strips or cubes to ensure quick and even cooking.
In a large bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken and all the vegetables to the bowl, tossing thoroughly until everything is evenly coated in the herb mixture.
Spread the mixture in a single layer on the prepared sheet pan, ensuring nothing is overcrowded so the vegetables roast rather than steam.
Bake for 18-22 minutes, or until the chicken is cooked through and the vegetables are tender and slightly charred.
Remove from the oven and serve immediately, optionally garnishing with fresh parsley or an extra squeeze of lemon.