Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Cut the chicken breast, zucchini, red bell pepper, and red onion into uniform bite-sized pieces.
In a large mixing bowl, whisk together the olive oil, lemon juice, apple cider vinegar, dried oregano, sea salt, black pepper, and garlic powder.
Add the chicken and chopped vegetables to the bowl and toss thoroughly until everything is evenly coated in the dressing.
Spread the chicken and vegetable mixture across the prepared baking sheet in a single, even layer to ensure proper roasting.
Place the sheet in the oven and roast for 15 minutes.
Remove the sheet briefly to toss the ingredients, then add the diced mango cubes to the tray and roast for an additional 5-10 minutes until the chicken is cooked through.
Divide the warm cooked quinoa into serving bowls, top with the roasted mango chicken and vegetables, and finish with a sprinkle of crumbled feta cheese.