Recipe(tried): A REALLY good Seafood Gumbo from a Texan

I make this recipe often. It is fantastic. It is very close (if not better) than Pappadeaux's.

SEAFOOD GUMBO
Roux:
1/2 cup cooking oil
1/2 cup flour
Put oil in a heavy pot and add flour. Over medium-low heat, stir constantly until it browns to the color of coffee; cook slowly.
2 stalks celery, chopped
2 onion, chopped
1 medium green pepper, chopped
1 cup chopped tomatoes
2 quarts hot water
Salt and pepper, to taste
2 cups cooked okra
2 pounds shrimp, peeled
1 pound crabmeat
1/2 to 1 teaspoon file powder
When roux has browned add celery, onions, and green peppers. Cook until wilted, add tomatoes, water, salt and pepper to taste and bring to a boil. After it is brought to a boil, add the okra lower the heat and cover and simmer for 45 minutes. Check the water level and make sure there is a good consistency, otherwise add a little more water and then add shrimp and crab. Cook an additional 30 minutes. Turn off the stove and add 1/2 to 1 teaspoon file. Serve
Prep Time: 15 minutes
Cooking Time: 1 hours 30 minutes