Position a rack in the middle of the oven and preheat the oven to 350 degrees F.
In a heavy bottomed pot or Dutch oven, heat 1 cup peanut oil over moderately-high heat until hot but not smoking. Slowly whisk in the flour until fully incorporated, making a roux. Cover the pot, place in the oven and cook for 2 hours, whisking every 15 minutes.
In a large stockpot, add the whole chicken, chicken wings, 3 chopped onions and a handful of black peppercorns. Add enough water to cover the chicken by 4 inches and bring to a boil. Turn down the heat and let simmer until the whole chicken is cooked, about 2 hours. Pull the whole chicken out, leaving the wings in to simmer for another hour. When the whole chicken is cool enough to handle, pull the meat and set aside. Strain the stock, discarding all solids, including the wings. You should have between 6 and 8 cups stock.
In a large pot, heat the remaining 2 tablespoons oil over moderately-high heat. Add the sausage and cook until golden brown, about 6 minutes, turning once. Remove the sausage and turn the heat down to moderate. Add the remaining 2 chopped onions and cook until softened, about 8 minutes. Whisk in the roux, slowly add the stock and simmer about 30 minutes. Add the reserved chicken and sausage and cook about 20 minutes. Season with salt and pepper. Serve over rice.
What Makes This Recipe Really Sing: Ask any New Orleanian and they will tell you gumbo is all about the roux. I have given you the secret to a perfect yet easy version. Also, organic chicken is a must here. It has much more flavor then most mass produced brands found in grocery stores.
BYOC: Okra is a traditional ingredient in gumbo, so if it is in season, chop into 1/3-inch pieces and add when you add the reserved chicken. Sometimes I add chopped kale just to make sure I am getting my veggies in.