Preheat the oven to 350 degrees F (175 degrees C).
Arrange the chicken pieces in a 10x15-inch enameled roasting pan. In a large skillet over medium high heat, fry the potatoes in 1/2-inch-deep oil until golden brown, then put them in the pan with the chicken.
Combine the vinegar, lemon juice, garlic, oregano, parsley, onion, salt and pepper with the 1/2 cup reserved frying oil and pour this mixture over the chicken and potatoes.
Bake in the preheated oven for 1 1/4 hours, basting the chicken and potatoes with the sauce mixture. Let rest for 5 minutes and serve hot.