Chicken Shawarma with Yogurt Sauce

Combine 1/4 cup yogurt, onion, 1 tablespoon lemon juice, 2 garlic cloves, coriander, cumin, allspice, pepper, 3/4 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 degrees 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 degrees 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 1/2 cup yogurt, 1 tablespoon lemon juice, 1 garlic clove, 1/4 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.