For the Brown Roux:
In a heavy 4- to 6-quart saucepan, being careful, bring the oil to the smoke point. Add the flour, ¼ cup at a time, letting it turn a dark, nutty brown before the next addition. Stir continuously so the flour doesn’t burn. When all of the flour is in and mixture is a nice brown color, remove from the heat. Stir in the onion, pepper, celery and garlic. This will start to cool off the roux, and bring out more color and add flavor. Transfer the roux to a bowl or container; when cool, refrigerate until ready to use. (Some of the oil will come to the top; mix it back in before using the roux.)
For the Creole Seasoning:
In a food processor or bowl, mix the salt, paprika, garlic, onion, black pepper and cayenne pepper together until thoroughly combined. Cover and store in a cool, dry place.
For the Gumbo:
In a heavy saucepan, heat the oil to the smoke point. Sauté the onions and red and green peppers until the onions are translucent. Add the okra if desired and sauté 1 minute longer. Add the garlic and 1 cup of vegetable stock to deglaze pan. Then add hot sauce, Worcestershire sauce, 2 teaspoons of Creole Seasoning, the remaining vegetable broth, salt, bay leaves, and thyme. Bring the mixture to a simmer; add 6 tablespoons of the Brown Roux. Return to a simmer for 5 minutes. Add the mixed greens; simmer for 45 to 60 minutes, until the greens are tender. Adjust seasoning if necessary.
To Assemble and Serve:
Ladle gumbo into warm bowls and top each with rice; sprinkle with gumbo filé.