Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel the sweet potato and cut into 1/2-inch cubes; chop the red bell pepper into bite-sized pieces.
Slice the chicken breast into even 1-inch chunks to ensure they cook at the same rate as the vegetables.
In a large mixing bowl, combine the chicken, sweet potato, broccoli, and bell pepper.
Drizzle with olive oil and lemon juice, then sprinkle with oregano, garlic powder, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are evenly coated in the oil and spices.
Spread the mixture in a single layer on the prepared baking sheet, ensuring nothing is overcrowded.
Roast for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender.
Serve immediately, optionally garnished with fresh parsley or an extra squeeze of lemon.