Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
In a large bowl, whisk together the olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Add the chicken breast, sliced zucchini, and chopped bell peppers to the bowl, tossing thoroughly until every piece is coated in the herb marinade.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, ensuring they aren't overcrowded so they roast rather than steam.
Roast for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and slightly charred.
Place the warm, cooked quinoa in a serving bowl and top with the roasted chicken and vegetables.
Finish the bowl by sprinkling the crumbled feta cheese over the top for a salty, creamy finish.