Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large bowl, toss the broccoli florets, sliced carrots, and sliced zucchini with half of the olive oil, a pinch of sea salt, and a pinch of black pepper.
Spread the vegetables in a single layer on the prepared baking sheet and roast for 18-20 minutes until tender and slightly caramelized.
While the vegetables roast, season the chicken breast evenly on both sides with the garlic powder, dried oregano, and the remaining sea salt and black pepper.
Heat the remaining olive oil in a large skillet over medium-high heat.
Place the chicken in the skillet and sear for 6-7 minutes per side, or until the internal temperature reaches 165°F (74°C) and the exterior is golden brown.
Remove the chicken from the heat and immediately drizzle with the fresh lemon juice to deglaze the pan slightly and coat the meat.
Serve the chicken alongside the roasted vegetables, drizzling any remaining pan juices over the top.