Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Cut the chicken breast into 1-inch bite-sized pieces and dice the sweet potato into 1/2-inch cubes.
Chop the red bell pepper into 1-inch pieces and break the broccoli into small florets.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Place the chicken, sweet potatoes, broccoli, and bell peppers on the prepared baking sheet.
Drizzle the lemon-herb dressing over the chicken and vegetables, tossing well to ensure everything is evenly coated.
Spread the mixture into a single layer on the tray to ensure even roasting and browning.
Roast for 20-25 minutes, or until the chicken is cooked through and the sweet potatoes are tender when pierced with a fork.
Remove from the oven and serve immediately, optionally garnishing with fresh parsley or extra lemon zest.