Gather all ingredients.

Make the tzatziki: Combine yogurt, cucumber, garlic, oil, dill, vinegar, lemon juice, salt, and pepper in a blender. Blend until smooth, then cover and refrigerate until needed.

Make the chicken: Whisk garlic, lemon juice, oil, oregano, vinegar, salt, and pepper together in a large glass or ceramic bowl. Add chicken and toss until evenly coated. Cover with plastic wrap and marinate in the refrigerator for 1 hour.

Preheat the oven's broiler and set the oven rack about 6 inches from the heat source. Line a rimmed baking sheet with foil.

Remove chicken from the marinade and place onto the prepared baking sheet.

Broil in the preheated oven until lightly browned and no longer pink in the center, 2 to 4 minutes per side. Transfer cooked chicken to a plate and let rest for 5 minutes.

While the chicken is resting, make the gyros: Heat a large nonstick skillet over medium heat. Cook each pita in the hot skillet until warm and soft, about 1 minute per side.

Top warm pitas with chicken strips, tzatziki, lettuce, tomato, and onion.

Enjoy!