Bring a large pot of water to a boil. Add the chicken breasts, a'atryaat, and a good pinch of salt and pepper. Boil the chicken for 20 minutes, until cooked through. Drain the chicken breasts and cool. When they are cool enough to handle, shred the meat with your fingers. In a pot, heat 3½ tablespoons (50 ml) of the olive oil over medium heat. Sauté the onions for 5 minutes, or until softened. Add the shredded chicken, sumac, pine nuts, and the remaining 3½ tablespoons (50 ml) of olive oil. Fry everything together for 5 minutes. Add salt and pepper to taste. Place a few spoonfuls of the shredded chicken mixture onto each flatbread. Fold the sides of the flatbread toward the inside over the filling, and then fold into a rectangular parcel. Heat a grill pan over high heat and cook the wraps for 2 minutes on each side until golden and crispy. Serve them warm with laban bi khyar.