Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Peel the sweet potato and cut it into 1/2-inch cubes; chop the broccoli into florets and the bell pepper into 1-inch pieces.
Slice the chicken breast into even 1-inch strips to ensure they cook at the same rate as the vegetables.
In a large mixing bowl, combine the chicken, sweet potato, broccoli, and bell peppers.
Drizzle the olive oil and lemon juice over the mixture, 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 seasonings.
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 reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Remove from the oven and serve immediately, perhaps with an extra squeeze of fresh lemon if desired.