Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch cubes to ensure even cooking.
Prepare the vegetables by chopping the broccoli into bite-sized florets, slicing the bell pepper into strips, and cutting the zucchini into half-moons.
In a large mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the cubed chicken and all the prepared vegetables to the bowl, tossing thoroughly until every piece is well-coated with the lemon-herb mixture.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is fully cooked through and the vegetables are tender with slightly charred edges.
Remove from the oven and serve immediately, adding an extra squeeze of fresh lemon if desired for added brightness.