Directions
Make the spice mix: Using mortar and pestle grind black pepper, dried mint, dried oregano, ground cinnamon, ground cumin, and ground nutmeg for 2 to 3 minutes. May be made 1 week ahead. Cover to store.
Make the tahini yogurt: Combine 3 tablespoons lemon juice, 1 tablespoon of the spice mix you just made, and garlic in medium bowl; stir to blend. Let stand 5 minutes. Whisk in yogurt and tahini. Season tahini yogurt to taste with salt. May be made up to 2 hours ahead. Let stand at room temperature.
Make the pomegranate relish: Mix pomegranate seeds, pistachios, parsley, 2 tablespoons olive oil, 1 tablespoon lemon juice in medium bowl. Season to taste with salt and freshly ground black pepper. May be made 2 hours ahead. Let stand at room temperature.
Make the chicken: Whisk grated onion, 2 tablespoons lemon juice, 2 tablespoons olive oil, and remaining spice mix in large bowl. Add chicken. Sprinkle with salt and pepper. Marinate at room temperature at least 1 hour and up to 2 hours.
Preheat broiler. Divide the chicken chunks between 6 skewer, threading them with out packing them too tightly. Sprinkle with salt and pepper. Place on small rimmed baking sheet. Broil chicken until cooked through, 5 to 6 minutes per side. Arrange kebabs on platter. Serve with tahini yogurt, pomegranate relish, and warm pita breads.