Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Rinse the quinoa under cold water and cook it in a small pot with one cup of water or broth until all liquid is absorbed and the grain is fluffy.
Dice the zucchini, red bell pepper, and red onion into uniform bite-sized pieces.
Toss the vegetables with half of the olive oil, sea salt, and black pepper on the prepared baking sheet and roast for 20 minutes until tender.
Season the chicken breast with the dried oregano and the remaining salt and pepper, then grill or pan-sear over medium-high heat until the internal temperature reaches 165°F.
Allow the chicken to rest for five minutes before slicing it into thin strips.
In a large mixing bowl, combine the cooked quinoa, roasted vegetables, and sliced chicken.
Whisk together the remaining olive oil and lemon juice, then drizzle the mixture over the bowl and toss gently to coat.
Garnish the dish with crumbled feta cheese and freshly chopped parsley before serving.