Making a dark roux for gumgo can be the toughest part of the whole process. So here is a tip for the perfect unburnt roux.
Mix your fat and flour in the castiron pot that you are going to make the gumbo in and place it in a 375 deg oven. Should take about an hour and the cooking process is a lot slower and even. Now it may not be traditional but if you have stood over the stove sturring a roux for 45 minutes only to have it burn in the last 30 seconds you’ll understand.
Got to use cast iron though so the heat is even.