Cook okra in 2 Tbsp butter in a large skillet over medium-high heat, stirring constantly, until lightly browned.
Combine remaining butter and flour in a large dutch oven, cook over medium high, stirring constantly until roux is chocolate colored-around 20-25 min (I say have a beer while doing this) Stir in green onions, celery and garlic, cook stirring constantly until veg is tender.
Add okra, water and the next 6 ingredients.
Bring to a boil, reduce and simmer uncovered 2 hours, stirring occasionally.
Peel and devein shrimp, add that and crab to okra mixture.
Simmer an additional 10 minutes, stirring occasionally.