Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the chicken breast into 1-inch cubes and chop the sweet potato, broccoli, and red bell pepper into bite-sized pieces.
In a small bowl, whisk together the extra virgin olive oil, fresh lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Place the chicken and vegetables on the prepared baking sheet and pour the lemon-herb marinade over the top, tossing well to ensure every piece is evenly coated.
Spread the mixture into a single layer to ensure even roasting and prevent steaming.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
Remove from the oven and serve immediately, drizzling any remaining juices from the pan over the chicken.