Preheat your oven to 400°F (200°C) and prepare a large baking sheet.
In a small bowl, whisk together half of the olive oil, the lemon juice, minced garlic, and dried oregano to create the marinade.
Place the chicken breast in a shallow dish, coat with half of the marinade, and let it sit for 10 minutes to absorb the flavors.
On the baking sheet, toss the broccoli florets, sliced bell peppers, and zucchini with the remaining olive oil, sea salt, and black pepper.
Roast the vegetables in the oven for 18-20 minutes until they are tender and the edges are slightly charred.
While the vegetables roast, heat a grill or grill pan over medium-high heat and cook the chicken for 6-7 minutes per side until fully cooked.
Slice the chicken and serve it immediately alongside the roasted vegetables, drizzling any remaining marinade over the plate.