For the chicken: Combine all ingredients except chicken in large baking dish. Add chickens and turn to coat. Cover and marinate in the refrigerator for 2 hours. Preheat oven to 375 degrees F. Remove chicken from marinade and sear skin side down in a large saute pan until golden brown, then turn and cook other side until golden brown. Place chickens on baking sheet and bake until cooked through, about 15 to 17 minutes. For the Relish: Combine all ingredients in a bowl.
For the Potatoes: Bake potatoes in a 375 degree F. oven until soft. Peel and place them in a warm bowl. Add butter and olive oil and mash with a fork until mixed but not smooth. Season with salt and fold in parsley.