Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the red bell pepper, zucchini, and red onion into uniform bite-sized pieces.
Place the chicken breast and chopped vegetables onto the prepared baking sheet.
Drizzle the olive oil over the chicken and vegetables, then sprinkle with sea salt, black pepper, and dried oregano.
Toss the vegetables to coat evenly and ensure the chicken is seasoned on both sides.
Roast in the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and slightly caramelized.
Remove from the oven and allow the chicken to rest for 5 minutes before slicing it into thin strips or cubes.
In a large mixing bowl, combine the cooked quinoa, roasted vegetables, and sliced chicken.
Drizzle with fresh lemon juice and toss everything together gently to combine.
Serve warm or at room temperature for a clean, nutrient-dense meal.