Preheat your oven to 400°F (200°C).
Chop the chicken breast and sweet potato into uniform bite-sized pieces to ensure even cooking.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Place the chicken, sweet potato cubes, and broccoli florets on a large parchment-lined sheet pan.
Drizzle the lemon-herb mixture over the chicken and vegetables, then toss with your hands or tongs until everything is thoroughly coated.
Spread the ingredients out into a single layer, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Bake for 20-25 minutes, or until the chicken is cooked through and the sweet potatoes are tender and lightly browned.