Add the onion, green pepper and celery to the pan, put on the lid and cook for 5 mins, stirring occasionally until softened a little. Stir in the garlic, spices, thyme and bay leaf and cook for 1 min until fragrant. Return the chicken and any juices to the pan with the flour, stirring to coat everything. Pour in the tomatoes and stock, and bring to the boil, cook for 5 mins, then add the okra and half the sage. Turn down to a simmer, put on the lid and cook for 10 mins. Then season and serve, scattering the rest of the sage over.