Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the zucchini, red bell pepper, and red onion into uniform 1-inch pieces.
Place the vegetables on the baking sheet, drizzle with half of the olive oil, and sprinkle with half of the sea salt and black pepper.
Roast the vegetables in the oven for 20 minutes, or until they are tender and have slightly caramelized edges.
While the vegetables roast, season the chicken breast evenly with the dried oregano, garlic powder, lemon zest, and the remaining sea salt and pepper.
Heat the remaining olive oil in a medium skillet over medium-high heat.
Add the chicken to the skillet and sear for 6-7 minutes per side, or until the internal temperature reaches 165°F (74°C).
During the last minute of cooking, pour the lemon juice over the chicken to deglaze the pan and coat the meat.
Remove the chicken from the heat and let it rest for 3 minutes before slicing and serving alongside the roasted vegetables.