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A heavy-bottomed pot is essential to prevent burning. Cold start the sausage in the pan, then cook over medium heat with a splash of oil to render the fat. Once browned and drained, the sausage's flavorful fat remains in the pot to begin the roux— a crucial step.
The roux is an equal parts mixture of oil and flour, cooked low and slow for about an hour until deep, chocolate brown. This dark roux is the flavor powerhouse of the gumbo, imparting a rich, nutty taste. Constant stirring and patience are key here; a hastily cooked roux can result in a burnt flavor, ruining the dish.