Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Peel the sweet potato and cut it into 1/2-inch cubes; slice the red bell pepper into strips and the zucchini into half-moons.
Cut the chicken breast into uniform 1-inch bite-sized pieces to ensure even cooking.
In a large mixing bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Add the chicken, sweet potato cubes, broccoli, peppers, and zucchini to the bowl and toss thoroughly until every piece is coated in the herb marinade.
Spread the mixture in a single, even layer across the prepared sheet pan, ensuring no pieces are overlapping.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender.
Serve immediately while hot, perhaps with an extra squeeze of fresh lemon if desired.