Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Slice the chicken breast into 1-inch bite-sized pieces and halve the baby potatoes to ensure they cook at the same rate.
In a small glass bowl, whisk together the extra virgin olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper to create the marinade.
Place the chicken pieces, halved potatoes, broccoli florets, and sliced red bell pepper onto the prepared sheet pan.
Drizzle the lemon-herb marinade over the chicken and vegetables, then toss thoroughly with your hands or tongs until every piece is well-coated.
Spread the ingredients out into a single, even layer, making sure the pan is not overcrowded so the vegetables roast and develop color rather than steam.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken is cooked through and the potatoes are fork-tender and golden brown.
Remove from the oven and let rest for 2 minutes before serving to allow the juices to redistribute.