In a small bowl, mix the Greek yogurt, garlic, lemon juice, olive oil, dill, salt, and pepper to make the tzatziki sauce.
Grill or pan-cook the chicken breasts until fully cooked, then slice them thinly.
Lay out the wraps and spread a generous spoonful of tzatziki sauce over each.
Top with sliced chicken, cucumber, tomato, and red onion.
Fold the wraps tightly and serve immediately.