Combine ¼ cup yogurt, onion, 1 tablespoon lemon juice, 2 garlic cloves, coriander, cumin, allspice, pepper, ¾ teaspoon salt and turmeric in a large bowl. Add chicken and rub the yogurt mixture into it. Cover and refrigerate for 1 hour or up to 3 hours.
Position racks in upper third and center of oven; preheat to 450°F. Coat a baking sheet with cooking spray.
Arrange the chicken in a single layer on the prepared baking sheet; discard any remaining marinade. Roast on the center rack until an instant-read thermometer inserted in the thickest part registers 165°F, about 20 minutes. Move the baking sheet to the top rack and turn the broiler to high. Broil until browned in spots, 3 to 5 minutes. Transfer the chicken to a clean cutting board and let rest for 3 minutes. Thinly slice.
Meanwhile, combine the remaining ½ cup yogurt, 1 tablespoon lemon juice, 1 garlic clove, ¼ teaspoon salt, cucumber and herbs in a small bowl. Divide the chicken among lavash halves. Serve with the yogurt sauce and lettuce and tomato, if desired.
Serving Size 6 servings
Servings 2
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.