Step 1Heat the oven to 450 degrees.
Step 2Heat 1/4 cup of the oil in a large skillet over low heat. Add the onions and cook until they're golden, stirring occasionally, 20 minutes. After 5 minutes, sprinkle on salt to taste.
Step 3Season the chicken pieces with salt and pepper, rubbing well into the skin.
Step 4Transfer the onions to 13x9-inch baking dish and place the chicken on top.
Step 5Bake, uncovered, 5 minutes. Reduce the heat to 375 degrees and bake 15 minutes more.
Step 6Drizzle a tablespoon or so of the remaining olive oil into a skillet. Heat the oil, then add the pine nuts. Cook over a medium-low heat, stirring frequently, until the pine nuts are browned, 10 minutes.
Step 7Mix together the sumac, allspice, cloves and pine nuts in a small bowl.
Step 8Remove the chicken from the oven and sprinkle on the sumac-pine nut mixture. Drizzle the remaining olive oil over the top and return the dish to the oven. Continue baking until the chicken is cooked, 20 to 25 minutes. Remove the chicken from the oven.
Step 9Heat the broiler. Transfer each chicken piece to a round of pita bread, or place all the chicken pieces over the large pita. Sprinkle the onions, with a small amount of the cooking liquid, on top and around the chicken. Broil the chicken 6 inches from the heat source until the skin is crispy, 5 minutes. Watch closely to prevent burning.