I lived in Lafayette La from late 70s till 1995.
I and most in S. La use roux from a jar. Preferably Savoie's but Kary's is not bad either. Buy dark roux..not the light stuff.
Putting tomatoes in gumbo is like putting beans in chili. just..NO! You use tomaote in sauce picante type cajun food.
Key to chicken/sausage gumbo is good quality sausage.
I usually buy skinless chicken thighs for gumbo, and season & lightly brown them beforehand. Bone-in or boneless.
Most cubed chicken from grocery store is white meat and lacks flavor.
In this part of Tx , a good sausage is Holmes Original and Burton brand , with Holmes being the better. I put equal parts (by weight) sausage and chicken.
For 4 hungry adults and some leftover, I'd use no less than 1 1/2 lbs each chick/sausage.
1 Large onion coarsely chopped.*
1-2 tablespoons Tony Chachere's original seasoning...green container. (this takes care of most of the salt, red pepper and garlic) You can add some more at the end of cooking if it's not seasoned enough.
1-2 green bell peppers, chopped into about 1/4"-3/8" chunks.*
3/4 to 1 cup chopped celery.*
(wife doesn't like okra so I don't use it)
Boil about 5-6 qts of water in a big pot.
Keep it at a low to medium rolling boil.
Stir in about 1/2 jar of roux, stirring constantly to COMPLETELY dissolve the roux.
Add 1/2 the Tony's.
Add browned chicken. When it has boiled about 20 minutes, add the sausage and add the rest of the Tonys.
Add the onions, pepper and celery. Reduce heat to slow boil, and cover loosely, leaving the lid slightly off center.
Skim grease off as it appears on top of the boiling mixture.
2 hours more cooking is more than enough for chicken sausage gumbo on stovetop.
*if this item is available, it is a good and acceptable substitute for the gumbo veggies. Onions, Celery, Green Peppers, Red Peppers. Just thaw it out before hand..never put frozen vegs into soup or gumbo..that will make the grease or oils clump up and it changes the taste.
For the smaller chunks, use:
but it also has parsley flakes in it.
This stuff lasts for months in the freezer.