Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized cubes and set aside.
Prepare the vegetables by chopping the broccoli into small florets, slicing the red bell pepper into thin strips, and cutting the zucchini into half-moons.
In a small mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper to create the marinade.
Place the chicken cubes and all the chopped vegetables onto the prepared sheet pan.
Drizzle the lemon-herb dressing over the chicken and vegetables, then use your hands or tongs to toss everything until thoroughly and evenly coated.
Spread the mixture out into a single layer across the pan, making sure the chicken pieces are not touching to ensure they brown properly.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly charred edges.
Remove from the oven and serve immediately while hot, perhaps with an extra squeeze of fresh lemon if desired.