In a bowl, combine yogurt, mayonnaise, lemon juice, garlic, spices, salt, and olive oil. Add the chicken and coat it thoroughly. Cover and refrigerate for at least 2–4 hours, preferably overnight.
Heat a grill pan or skillet over medium-low heat. Cook the chicken for 5–7 minutes on each side until fully cooked. Then, increase the heat briefly to char the chicken. Let it rest for 5 minutes before slicing it into strips.
In another bowl, combine onion, cucumber, tomatoes, and olives. Season them with salt, pepper, olive oil, and lemon juice. If using feta cheese, add it to the mixture and toss gently.
Mix yogurt, olive oil, lemon juice, garlic, herbs, and salt. Add grated cucumber (well-drained) and stir. Chill until ready to use.
Warm the tortillas in a pan or microwave. Layer them with lettuce, chicken, Greek salad, and tzatziki sauce. Wrap them tightly and serve immediately.
