In a large bowl, whisk together olive oil, lemon juice, garlic, oregano, paprika, salt, and pepper. Add the chicken and toss to coat evenly. Let it marinate for at least 20 minutes.

Heat a grill pan or skillet over medium heat. Cook the chicken for 5 to 6 minutes per side, until golden and fully cooked through.

Remove the chicken from the pan and let it rest for 5 minutes. Slice into strips.

While the chicken rests, warm the cooked rice or quinoa and prepare the vegetables.

To assemble, divide the rice or quinoa among four bowls. Top with sliced chicken, tomatoes, cucumber, red onion, olives, and parsley.

Finish with tzatziki and feta if using. Serve immediately or store for meal prep.