In a mixing bowl, whisk together olive oil, lemon juice, minced garlic, oregano, paprika, salt, pepper, and optional red pepper flakes to create a zesty marinade. Add the boneless, skinless chicken breasts, ensuring each piece is fully coated. Cover the bowl with plastic wrap and let the chicken marinate at room temperature for 15–45 minutes.

While the chicken marinates, chop cucumbers, seeded tomatoes, bell pepper, and red onion into uniform pieces and combine them in a separate bowl. Add freshly chopped parsley and crumbled feta for a burst of flavor. Drizzle lemon juice, season with salt and pepper, and mix gently to combine. Let the salsa sit for 10–15 minutes.

Heat a skillet over medium-high heat until hot. Remove the chicken from the marinade, allowing any excess to drip off, then place it in the skillet. Cook for about 6-9 minutes per side, or until the chicken is golden brown and its internal temperature reaches 165°F.

While the chicken finishes cooking, warm your pita bread by either charring them over a gas flame for about 30 seconds on each side or wrapping them in foil and heating in a preheated 350°F oven for about 5 minutes.

Once the chicken is cooked, remove it from the skillet and slice it into strips. Place warm pitas on plates and fill each one generously with sliced chicken. Top with salsa and finish with tzatziki sauce.