Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Halve the baby potatoes and cut the chicken breast into uniform 1-inch pieces to ensure even cooking.
Place the potatoes on the prepared sheet pan, drizzle with half of the olive oil and a pinch of salt, then roast for 10 minutes.
Remove the pan from the oven and add the chicken pieces, broccoli florets, and sliced red bell peppers.
In a small jar or bowl, whisk together the remaining olive oil, lemon juice, oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb mixture over the chicken and vegetables, tossing everything thoroughly with tongs to coat.
Return the pan to the oven and roast for an additional 15 to 20 minutes until the chicken is cooked through and the potatoes are fork-tender.
Garnish the dish with freshly chopped parsley and an extra squeeze of lemon if desired before serving.