• 8 oz. andouille sausage, halved lengthwise and sliced thin
• 6 oz. okra, stemmed and cut into 1-in. pieces
Adjust oven rack to lowest position and heat oven to 350 degrees. Toast 3/4 cup flour in Dutch oven on stovetop over medium heat, stirring constantly, until just beginning to brown, about 5 minutes. Off heat, whisk in oil until smooth. Cover, transfer pot to oven, and cook until mixture is deep brown and fragrant, about 45 minutes. (Roux can be refrigerated in airtight container for 1 week. To use, heat in Dutch oven over medium-high heat, whisking constantly until just smoking, and continue with recipe.)
Transfer Dutch oven to stovetop and whisk cooked roux to combine. Stir in onion, bell pepper and celery, and cook over medium heat until softened, abut 10 minutes. Stir in remaining 1 tablespoon flour, garlic, thyme and cayenne, and cook until fragrant, about 1 minute. Add tomatoes and cook until dry, about 1 minute. Slowly whisk in broth and fish sauce, scraping up any browned bits and smoothing out any lumps. Season chicken with pepper, then add to pot and bring to boil.
Reduce heat to medium-low and simmer, covered, until chicken registers 175 degrees, about 30 minutes. Using large spoon, skim fat from surface, then transfer chicken to large plate. When chicken is cool enough to handle, shred into bite-size pieces using 2 forks and return to pot; discard bones.