Make the Dry Roux:

1. Preheat oven to 350F. Line a sheet pan with parchment, if desired. Keeping 2 inches (5cm) from the edges, distribute 3 cups All-Purpose Flour. Place the pan in the preheated oven, and using a bench scraper or knife, break up the flour, as it becomes compacted in the dry oven, every 30 minutes and stir around. Maintain the two-inch margin to prevent burning.
2. Between 1 1/2 and 2 1/2 hours, the flour will be the the color of a light caramel, or possibly beach sand, kind of a medium tan. Remove and cool
3. Sift 1 cup of the dry roux into a bowl to use for the gumbo, and reserve the rest for other purposes.

Make the Gumbo:

1. Prepare the ingredients: Slice the sausage, chop the vegetables, mix together the Smoked Paprika, garlic powder, onion powder, oregano, thyme and cayenne pepper.
2. Over medium heat, place a large, heavy pot, such as an enameled castiron soup pot. Pour 1 Tbsp Cooking oil, followed by the sliced andouille. Stir the andouille as it browns to be sure both sides are browned. Remove the slices to a plate.
3. Into the pot, pour the other tablespoon of oil, and place the chopped onion, celery and green pepper. Saute for about 2 minutes, then add salt and pepper, HALF the spice mix, and the dry roux. Stir the roux into the vegetable mix until it is evenly distributed.
4. Pour in the canned tomatoes, and 2 cups (480ml) of the stock. Stir (or you may need to whisk a bit), until the liquid works into the roux and it thickens. Follow with half the remaining stock, working it into distribute, then the other half of remaining stock. Add the two bay leaves.
5. Simmer gumbo 45 minutes. Taste after about 15 minutes and add additional spice mix, if desired. Add the shrimp and Gumbo File. Continue to simmer until shrimp are fully cooked, about 3 minutes.
6. Serve.