There are about a million different ways to make gumbo and also combos of meats and veggies. use what you like. Read different recipes. The main key: time, time, time and more time!
I use a dry roux and I make my own. It's just flour, folks. I use about a cup in my gumbo (yes, that's a lot- no, I don't care if you think so).
Note: it freezes fine so make a bunch and freeze it. It's great for soups too.
Turn your burner on medium-low (resist the urge to do it faster) and slooowly let it brown. it will take an hour or more. Stir every few minutes. This is almost done- I like it a bit darker.
I use about a 6 onions and 3 bell peppers- give or take. Also use celery. Satee until they're super soft and then add what herbs and spices you use. Sprinkle the roux on about 1/4 cup at a time and stir to coat the veggies. Add water or broth to just cover it and let simmer at least half an hour, preferable longer.
It'll get very thick. Add a bit more water and okra. Simmer another half hour or so.
After that you add your meats in stages and simmer all day. Seriously. Do not plan on eating the Gumbo the day you start it. Nuh-uh, big no no.
This is how mine looked at the end of day 1. I let it simmer from Noon until about 7pm.
We did this while it cooled :)
After it cools enough sprinkle with File put it in the fridge over night. It's KEY to let it sit at least one night. More is even better. The flavors meld in gumbo.
The next morning I pull it out and scrape the oil off the top, then heat it back up. It's good to let it simmer again about an hour or so before you serve.
Don't freak out if it looks like this (above). It always looks kinda iffy in the pot. :)
Serve over rice- DELISH!
If you want more on what I put in it and my steps leave me a comment and I'll send you my "outline." No recipe, gumbo is personal!