In a large bowl, whisk together olive oil, lemon juice, minced garlic, oregano, paprika, kosher salt, and black pepper. Add the chunks of chicken breast, ensuring they are well coated in the marinade. Cover and refrigerate for at least 15 minutes, ideally for 30-45 minutes.

In a separate bowl, combine chopped Persian cucumbers, halved cherry tomatoes, diced red bell pepper, and red onion. Toss in chopped parsley and crumbled feta, drizzle with olive oil and lemon juice, and season with salt and pepper. Mix gently and let sit.

Heat a skillet over medium-high heat. Add the marinated chicken in a single layer. Cook undisturbed for about 3-5 minutes until golden brown, then flip and cook for another 3-4 minutes, or until the chicken is cooked through.

While the chicken is cooking, warm the whole wheat pitas on a griddle or skillet over medium heat for about 1-2 minutes per side until soft.

Once the chicken is cooked and pitas are warm, place a portion of chicken inside each pita, followed by the cucumber salsa and a dollop of tzatziki.