Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Slice the chicken breast into uniform 1-inch cubes to ensure even cooking throughout the medley.
Chop the bell pepper, zucchini, and red onion into bite-sized pieces and mince the garlic cloves finely.
In a large mixing bowl, combine the cubed chicken, chopped vegetables, and minced garlic.
Drizzle the olive oil over the mixture and sprinkle with dried oregano, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are well coated with the oil and seasonings.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the ingredients are not overcrowded.
Roast for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender and lightly browned.
Remove from the oven and immediately drizzle with fresh lemon juice to brighten the flavors before serving.