Put the chicken in a large stockpot and cover with 3 - 4 quarts cold filtered water. Bring to a boil over medium high heat and then simmer for about 1 hour over medium heat, skimming impurities off the top as it simmers. Pull the chicken from the broth and set aside to cool, preferably in a bowl and cover with foil until ready to shred. Cover the broth and save until needed. Once cool enough shred the chicken and discard the bones.
Meanwhile, mix the spices and set aside.
Wash, rinse and dry the green bell pepper and tomatoes (if not canned) before prepping. Rinse the celery. If fire-roasting the tomatoes, cut in half, remove the cores and deseed. Place under the broiler for about 10 minutes. Let cool a bit then remove the skins and chop. If using canned whole tomatoes, remove each tomato and cut out the core, deseed and chop. Save the tomato juice from the can. You need 2 cups/16 ounces of flesh and juice.
Prep the Cajun mirepoix (diced celery, green bell pepper and onion) and set aside.
In a large skillet, heat the 2 tablespoons of olive oil (EVOO) over medium high/high heat. Add the frozen or fresh okra and stir occasionally for about 10-15 minutes. Fry the okra until all the stickiness is gone.
Slice the Andouille sausage and set aside.
In a large Dutch oven, melt the 1/2 cup oil for the roux over medium heat. Add the oat flour and stir continuously with a wooden or silicon spatula until a dark brown roux develops.
Add the mirepoix - diced onions, celery and green bell peppers. Stir occasionally for about 15 minutes, allowing the mixture to caramelize on the bottom to develop deep flavors.
Add the tomatoes, fried okra and sausage. Reduce heat to medium and cook for another 15 minutes, stirring occasionally.
Add the spices and stir.
Strain the chicken broth and add it to the gumbo in the Dutch oven (as much as fits in the pot). Save the rest. Stir well and bring to a slow boil. Lower heat and simmer uncovered for about 1 1/2 hours. About an hour after cooking add the rest of the broth if there is room in the pot.
Twenty minutes before serving add the shredded chicken and adjust the seasoning (usually about 1-2 tsp salt).
Discard the bay leaf.
Serve in a bowl with rice and a dash of your favorite hot sauce.