Here's how we cook a gumbo in Southwest Louisiana. Nobody on this side of the state uses Andouille, we use what I call a "Cajun style" sausage. Many of the local meat markets around here make it. I'm not sure of the difference between it and andouille but there are differences. 99% of the gumbos you eat over here use jarred roux. Why you ask? Cause ain't nobody got time fo dat!
1 hen chicken, cut into 8-10 pieces
1 lb sausage, sliced
1 medium to large onion, diced
1 green bell pepper, diced
1 jar roux
1 bunch green onions
salt, black pepper, red pepper, and *MAYBE* some garlic, to taste
water or chicken stock
cooked white rice
Fill your gumbo pot about half full with water or stock, and bring that to a low boil. Start adding your roux one spoonful at at time, stirring to dissolve it. Its gonna take a while and look like shit but just keep adding it and stirring. Depending on what size pot you have (I'll check mine later and tell you what size it is) you're gonna want to add 1/2 to 3/4 of the jar of roux. You're shooting for a coffee colored liquid.
Once the roux has come together, let that boil uncovered for at least an hour. Supposedly this makes it taste better. I think it "cooks" the roux but i have absolutely no science to back this up.
After the roux and water have boiled for a while, add it everything else. The chicken, sausage, onion, pepper, and seasonings. The whole shooting match. Cook this uncovered at a low boil until the hen is falling off the bone.
At this point you can serve it as is, or do the right thing and debone all that chicken. Always taste and adjust your seasonings at the end. Depending on who made your sausage you may need to cut back on the red pepper and salt. Oh, and toss in those green onions about 10-15 minutes before you serve.
Serve over steamed white rice. Do not serve over Uncle Ben's or Minute rice or any of that shit. Pickled okra, file (pronounced FEE-lay), and potato salad all go well with a gumbo like this. I have cooked gumbo like this many times, and once for about 50 people. Got lots of compliments that time.
I ain't saying this is the only way to cook a gumbo, just how we do it down here. Later when I have more time I'll answer questions or add to this.
EDIT: Fixed a few things.