Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the chicken breast, sweet potato, zucchini, and bell pepper into uniform 1-inch pieces to ensure even cooking.
In a small bowl, whisk together the olive oil, minced garlic, lemon juice, sea salt, black pepper, and dried oregano.
Place the chicken and all vegetables in a large mixing bowl, pour the lemon-herb dressing over them, and toss until everything is well coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the pieces aren't too crowded so they roast rather than steam.
Bake for 20-25 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
Remove from the oven and serve immediately, perhaps with an extra squeeze of fresh lemon for a bright finish.