In a bowl, whisk together ¼ cup of olive oil and the juice of 1 lemon, seasoning it with salt, pepper, and optional herbs. Coat the chicken in the marinade and marinate for at least 30 minutes.

Heat a skillet over medium-high heat. Add the marinated chicken and cook for 6-8 minutes on each side, until golden brown and cooked through.

Transfer cooked chicken to a cutting board, cover loosely with foil, and let rest for 5-10 minutes before slicing.

Distribute cooked rice or quinoa into serving bowls and layer with shredded romaine, grape tomatoes, cucumber, red onion, and feta cheese.

Drizzle tzatziki sauce over the bowls and optionally top with remaining marinade juice before serving.