Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Slice the baby potatoes into halves and chop the chicken breast into uniform 1-inch bite-sized pieces.
In a large mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken pieces, halved potatoes, broccoli florets, and sliced red bell pepper to the bowl, tossing thoroughly until every piece is coated in the herb marinade.
Spread the mixture out onto the prepared sheet pan in a single layer, making sure not to overcrowd the ingredients so they roast rather than steam.
Place the pan in the center of the oven and roast for 20 to 25 minutes, tossing the ingredients halfway through, until the chicken is cooked through and the potatoes are golden and tender.
Remove from the oven and serve immediately while hot, optionally finishing with a squeeze of fresh lemon.