In a large Dutch oven or large deep cast-iron skillet, heat oil over medium-high heat. Add flour, and whisk vigorously until combined and mixture is smooth. Reduce heat to low, and cook, stirring constantly with a flat-bladed spoon and scraping bottom of pot, until mixture resembles the color of peanut butter, 15 to 20 minutes. (As roux darkens, become increasingly vigilant about stirring.)
Gradually add 8 cups hot water to roux, whisking until combined and smooth. Add chicken, bell peppers, yellow onion, celery, garlic, and bay leaves. Increase heat to medium-high, and bring to a boil. Reduce heat to medium, and simmer until chicken is tender, about 45 minutes. Remove chicken from pot, and let cool enough to handle.
Stir andouille, green onion, Worcestershire, Creole seasoning, and salt into vegetable mixture. Simmer, stirring occasionally, until thickened and bubbly, about 30 minutes.
Shred chicken, discarding skin and bones. Stir meat into stew. Discard bay leaves. Serve with rice. Garnish with parsley, celery leaves, and Creole seasoning, if desired.
Recipe by Louisiana Cookin' at https://louisianacookin.com/classic-chicken-stew/