Preheat the oven to 400 degrees F.
Season the chicken inside and out with salt and pepper. Truss the chickens and brush each one with 2 tablespoons olive oil. Place in 1 or 2 roasting pans and roast until browned but only half-cooked, about 40 minutes.
Meanwhile, in a small bowl, combine the 4 tablespoons black pepper, a pinch of salt and the mustard and stir well to combine. Drizzle in the 1 tablespoon olive oil and mix well.
Once the chickens are half-cooked, remove from the oven and brush each with the black pepper and mustard mixture. Return to the oven and continue roasting until the juices run clear from a pricked spot, about another 30 minutes. Let rest 10 minutes before carving. While the chicken rests, in a medium-sized bowl, combine the parsley, red onion, tomatoes, remaining 3 tablespoons oil, sherry vinegar and salt and pepper, to taste, and toss well to combine.
Allow 1 breast and 1 leg per portion. Drizzle each portion with the pan juices and hot chili oil, top with the parsley salad and serve immediately.
In a small saucepan, combine the oil, pepper and chili flakes. Heat to 140 degrees F and simmer for 10 minutes. Remove from heat and allow to sit overnight or for 8 hours. Strain out solids.
Recipe copyright 2000, Mario Batali. All Rights Reserved.