Cook rice first, and while it is cooking, cook shrimp. To cook shrimp, bring water to a boil; add shrimp and boil for 6 8 minutes until color changes to pink; rinse in cold water (to stop cooking), and drain.
To prepare stew, squeeze juice of half lemon over cooked shrimp and set aside. Put oil in 6 litre saucepan and cook onion on medium heat until it is softened and translucent, 6 8 minutes. Add garlic, chopped peppers, celery, thyme, and file seasoning and cook for 5 more minutes. Add tomato, wine, pepper flakes, shrimp cooking liquid, fish stock, paprika, Worcestershire sauce, and salt. Simmer for 10 minutes and taste to determine the level of "heat" from the peppers. Add more if necessary. If you want to thicken it, add cornstarch mixture and simmer for 3 4 minutes. Add half cup parsley. The stew can be made to this point and held for several hours. Add the cooked shrimp just before you are ready to serve. Add shrimp. When it is heated through, squeeze remaining lemon juice over it and serve.