In a medium mixing bowl, combine Greek yogurt, minced garlic, lemon juice, and grated cucumber. Mix until smooth and creamy, then set aside for 10 minutes.

Add chopped herbs, salt, and pepper to the tzatziki sauce. Adjust seasoning to taste, then set aside.

In a large bowl, add cooked shredded chicken and pour the tzatziki sauce over it. Gently combine without over-mixing.

Place mixed greens on plates or bowls, or cut pita bread in half for easy stuffing.

Top greens or fill pita pockets with the tzatziki chicken mixture. Garnish with remaining herbs or cucumber slices. Serve immediately.