Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with paper towels and cut into uniform 1-inch bite-sized pieces to ensure even roasting.
Prepare the vegetables by slicing the zucchini into half-moons, chopping the red bell pepper into 1-inch squares, and cutting the red onion into thin wedges.
In a large mixing bowl, combine the chicken pieces and chopped vegetables.
Drizzle with extra virgin olive oil and sprinkle with dried oregano, garlic powder, sea salt, and black pepper.
Toss the mixture thoroughly until every piece of chicken and vegetable is evenly coated with the oil and spices.
Spread the mixture out in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.
Remove from the oven and garnish with freshly chopped parsley before serving warm.