In large enameled cast-iron casserole, whisk flour with 1/2 cup of oil until smooth. Cook roux over moderately low heat, whisking often, until deep brown, about 1 hour. Keep stirring during this time, but you can also use the time to shred chicken and chop vegetables.Add onion, celery, bell peppers and garlic to roux and cook over moderately low heat, stirring, until onion is translucent, about 20 minutes.Gradually add stock to roux/vegetable mix, whisking until smooth. Add andouille, bay leaves, jerk paste, thyme and paprika and bring to simmer. Cook over low heat for 45 minutes, stirring occasionally.Add okra to pot and simmer until tender, 15 minutes. Stir in chicken meat and season gumbo with salt, pepper and Tabasco. Discard bay leaves, ladle gumbo over rice, garnish with the scallions and serve with Tabasco.