Whisk together olive oil, fresh lemon juice, minced garlic, dried oregano, salt, and black pepper in a medium bowl. Add chicken, ensuring it's well-coated. Marinate for at least 20 minutes.

Heat a large skillet over medium-high heat with a splash of olive oil. Add marinated chicken and cook for 6-8 minutes on each side until golden brown and reaches 165°F (75°C). Let it rest.

Cook quinoa according to package instructions, then fluff with a fork.

Slice the rested chicken and assemble by placing quinoa in bowls, topping with chicken, cherry tomatoes, cucumber, red onion, and olives.

Drizzle the tahini dressing over the bowls, then add feta cheese and parsley.