Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with a paper towel to ensure a good sear, then cut it into 1-inch bite-sized cubes.
Slice the red bell pepper into thin strips and break the broccoli into bite-sized florets.
In a large mixing bowl, combine the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken cubes, broccoli, and bell peppers to the bowl and toss thoroughly until every piece is evenly coated with the lemon-herb mixture.
Spread the chicken and vegetables in a single, even layer on the prepared baking sheet, making sure not to overcrowd the pan so they roast rather than steam.
Roast in the center of the oven for 15 to 18 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.
Remove from the oven and let rest for 2 minutes before serving to keep the chicken juicy.