Begin by preheating your grill pan or outdoor grill to medium-high heat.
In a medium bowl, combine the olive oil, dried oregano, garlic powder, smoked paprika, sea salt, and black pepper to create a flavorful marinade.
Add the chicken breasts to the bowl, coating them well with the spice mixture. Allow the chicken to marinate for about 15 minutes.
Once marinated, grill the chicken for approximately 6-7 minutes on each side, or until the internal temperature reaches 165°F (75°C). After grilling, remove it from the heat and let it rest for a few minutes. Slice the chicken into strips.
While the chicken rests, warm the pita breads on the grill for about 1-2 minutes on each side.
Take each warm pita pocket and spread a generous amount of tzatziki sauce on the interior.
Next, layer each pita with a handful of mixed greens, followed by the sliced grilled chicken, halved cherry tomatoes, diced cucumber, and thinly sliced red onion.
For an extra burst of flavor, you can sprinkle crumbled feta cheese over the top of the filling if desired.
Finish by garnishing with the chopped fresh parsley.
Serve the pita pockets immediately while they are warm.
Notes
Feel free to customize the vegetables and toppings to your liking.