Flour and oil. Every restaurant I worked in made both blonde and dark roux ahead of time and added it later on to whatever we were making at the appropriate time...early in the process for dark roux with soups, sauces or gravies (to cook the roux taste out) and late in the process with blonde roux for cream sauces (becamel). We make a lot of those roux and store them in containers. That's the same as using jar roux. I used jar roux at home and I can't tell the difference either.
whoa... not sure what set you off ( and it’s ok if you think your gumbo is better than mine even if it isn’t) but was having a little fun with the jar roux comment as it wasn’t directed at you..it was quite the topic here for quite a while ....that may have been before you were active here which may explain you talking out of your ass on this one
Seriously, I would marinate it over night in milk and roast it in a cast iron pot. On top of tomatoes, onions, garlic with a little water. After you cut up and season the bird and brown the bird.