Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Dice the Yukon Gold potato and carrots into 1/2-inch cubes to ensure they roast at the same rate as the protein.
Cut the chicken breast into bite-sized pieces and place them on the sheet pan along with the potatoes, carrots, broccoli florets, and sliced red onion.
In a small mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb dressing over the chicken and vegetables, tossing thoroughly with your hands or tongs to coat every piece.
Spread the mixture into a single even layer, making sure not to overcrowd the pan so the vegetables become tender and golden rather than steamed.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are fork-tender.
Remove from the oven and garnish with finely chopped fresh parsley before serving.