Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Slice the bell peppers, zucchini, and red onion into bite-sized pieces and spread them across the baking sheet.
Drizzle the vegetables with half of the olive oil and a pinch of sea salt, then roast for 18-20 minutes until tender and caramelized.
While the vegetables roast, season the chicken breast with dried oregano, sea salt, and black pepper.
Grill the chicken over medium-high heat for approximately 6-7 minutes per side until the internal temperature reaches 165°F.
In a small glass jar, whisk together the remaining olive oil, lemon juice, and lemon zest to create the dressing.
Slice the grilled chicken into thin strips.
Place the baby arugula in a large bowl, top with the warm roasted vegetables and grilled chicken, and drizzle with the zesty lemon vinaigrette before serving.