Preheat your oven to 400°F (200°C) and heat a grill pan or outdoor grill to medium-high heat.
Chop the zucchini, bell peppers, and red onion into bite-sized pieces.
Toss the chopped vegetables with 0.5 tbsp of olive oil, half of the sea salt, and half of the black pepper on a large baking sheet.
Roast the vegetables in the oven for 18-20 minutes until they are tender and show slight charred edges.
In a small bowl, whisk together the remaining 0.5 tbsp of olive oil, lemon juice, garlic powder, oregano, and the remaining salt and pepper.
Brush the chicken breast thoroughly with the lemon-herb marinade.
Grill the chicken for 6-7 minutes per side, or until the internal temperature reaches 165°F (74°C).
Remove the chicken from the grill and let it rest for 5 minutes to lock in the juices before slicing.
Serve the sliced chicken alongside the roasted vegetables for a clean and satisfying meal.