Preheat oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Dice the chicken breast and sweet potato into uniform 1-inch cubes to ensure even cooking.
Chop the broccoli into small florets and slice the red bell pepper into bite-sized pieces.
In a small bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, oregano, salt, and pepper.
Arrange the chicken and all the vegetables on the prepared sheet pan in a single layer.
Drizzle the lemon-herb dressing over the chicken and vegetables, then toss to coat every piece thoroughly.
Roast in the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Serve immediately or portion into a meal prep container for a healthy grab-and-go lunch.