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 1-inch bite-sized pieces and slice the baby potatoes into halves or quarters so they cook quickly.
Chop the broccoli into bite-sized florets and dice the red bell pepper into 1-inch squares.
In a large mixing bowl, whisk together the extra virgin olive oil, fresh lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken pieces, potatoes, broccoli, and bell peppers to the bowl and toss thoroughly until every piece is well-coated in the herb marinade.
Spread the mixture in a single, even layer on the prepared sheet pan, making sure not to overcrowd the ingredients so they roast rather than steam.
Roast in the center of the oven for 20 to 25 minutes, tossing the ingredients halfway through, until the chicken is cooked through and the potatoes are golden and tender.