Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Peel the sweet potato and dice into 1/2-inch cubes; chop the broccoli into bite-sized 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 pepper.
Drizzle with the extra virgin olive oil and sprinkle with sea salt, black pepper, garlic powder, and dried oregano.
Toss everything thoroughly until the chicken and vegetables are evenly coated in oil and spices.
Spread the mixture in a single layer on the prepared sheet pan, making sure not to overcrowd the pan so the vegetables can crisp up.
Roast in the center of the oven for 20 to 25 minutes, tossing halfway through, until the chicken is cooked through and the sweet potatoes are tender.
Remove from the oven and drizzle the fresh lemon juice over the entire tray to brighten the flavors before serving.