Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast and sweet potato into uniform 1-inch cubes to ensure they cook at the same rate.
Chop the broccoli into bite-sized florets, slice the red bell pepper into strips, and cut the zucchini into half-moons.
In a small mixing bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Place the chicken cubes and all the chopped vegetables onto the prepared sheet pan.
Drizzle the lemon-herb dressing over the ingredients and toss thoroughly with your hands or tongs until every piece is well-coated.
Spread the mixture into a single, even layer, ensuring the pan is not overcrowded so the vegetables roast rather than steam.
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.