For the gumbo:
1) Heat a large Dutch oven over medium-high heat and add the vegetable oil. Add the sausage and cook, stirring occasionally, until browned and much of the fat is rendered. Remove the sausage to plate with a slotted spoon.
2) While the sausage browns, pour a good amount of flour into a shallow baking dish, and season with salt and pepper. Dredge the chicken with the flour and add to the Dutch oven, in batches if necessary, and cook until brown on both sides. Remove to the plate with the sausage.
3) Add the 70g flour to the Dutch oven and cook, stirring constantly, until light golden brown. Add the onions, peppers, and celery to the Dutch oven and cook, stirring, about 2 minutes. Stir in the okra and the garlic and cook, stirring, about 2 minutes.
3) Strip the leaves from the thyme into the Dutch oven, and stir in the bay leaves, red pepper flakes, and 1.5L broth. Crush the tomatoes through your hands into the pot. Return the chicken and sausage to the pot, bring to a boil, reduce the heat, and simmer, uncovered, 25 to 30 minutes, until the chicken is cooked through. Stir in some additional chicken to thin the sauce a bit, if desired.
4) Stir in the vinegar, spring onions, and parsley, taste, and adjust the seasoning.
For the rice:
1) Put the rice in a medium saucepan with a cover. Stir in the water or broth, salt, and pepper. Smooth the rice to make an even surface, cover and heat over low to medium-low heat until all the liquid has been absorbed and rice is tender, about 15 to 20 minutes.