Preheat oven to 400 degrees. Slice the red onion and bell peppers. Cut the eggplant and the tomatoes into 1 inch chunks. Place the red onions, bell peppers, eggplant and tomatoes into a 9x13 baking dish. Slice the chicken into very thin strips and add to the baking dish with the vegetables.
In a bowl mix the garlic, olive oil, lemon juice, oregano, salt and black pepper. Pour the mixture over the chicken and vegetables. Mix until everything is well coated in the dressing.
Rorast the chicken in the preheated oven for 1 hour stirring every 20 minutes. After roasting top with crumbled feta cheese and chopped fresh parsley. Stuff the mixture into the pita pockets and enjoy!