Marinate the chicken by combining olive oil, oregano, garlic powder, salt, and pepper. Coat the chicken and let it sit for 15-30 minutes.
Grill the marinated chicken for 6-7 minutes on each side until it reaches 165°F. Let it rest for 5 minutes before slicing.
In a large bowl, combine quinoa, cherry tomatoes, cucumber, red onion, feta cheese, Kalamata olives, and parsley. Toss gently.
Assemble the bowl by placing quinoa salad in each bowl, topping with sliced chicken, and drizzling with lemon juice.