In a large bowl, combine Greek yogurt, olive oil, minced garlic, dried oregano, paprika, lemon juice, salt, and pepper. Stir well to create a marinade.
Cut the chicken breasts into thin strips and add them to the marinade. Toss to coat evenly. Cover with plastic wrap and refrigerate for at least 1 hour (or overnight for best flavor).
Preheat a grill or grill pan over medium-high heat. Remove chicken from the marinade and grill for about 5-7 minutes on each side, or until the chicken is cooked through and has nice grill marks. Ensure the internal temperature reaches 165°F (75°C).
Once cooked, let the chicken rest for a few minutes before slicing into bite-sized pieces.
Warm the whole wheat pita breads on a hot pan for about 30 seconds on each side until soft and pliable.
Assemble the gyros by placing sliced chicken in the center of each pita bread.
Top with diced cucumbers, tomatoes, red onion, and shredded lettuce.
Garnish with fresh parsley and an extra dollop of Greek yogurt if desired.
Notes
Serve each gyro on a plate with a side of tzatziki sauce and extra diced vegetables for a colorful and inviting meal. Wrap the bottom of the pita in parchment paper for easier handling.