Step 1Place all of the spices in a mixing bowl and whisk to blend together thoroughly. Store the spice blend in a closed container until needed. This makes about 2 1/2 tablespoons Creole seasoning.
Step 1Melt the butter in a large heavy-bottom saucepan over medium heat. Stir in the flour slowly to form a roux. Cook, stirring frequently until the roux darkens to a deep caramel color, and watch that the roux does not burn on the bottom. Stir in the bell peppers and celery and cook for 30 seconds, then slowly add the vegetable broth, whisking until fully incorporated.
Step 2Stir in the Creole seasoning, salt, black pepper, crushed chile, chili powder, thyme leaves, bay leaf, file powder and garlic. Simmer gently over low heat for 45 minutes to develop the flavor, stirring and scraping the bottom to prevent burning, and skimming any fat that rises to the surface. Remove from heat. This makes about 4 1/2 cups base; the base can be made ahead of time and refrigerated at this point.
Step 1Bring a large pot of water to a boil. Add the linguine and cook to al dente according to the package directions. Drain the pasta and shock with ice water to stop the cooking. Set aside.
Step 2Heat a large heavy-bottom pot over medium-high heat and add the olive oil. Stir in the onions, bell peppers and garlic and cook briefly. Add the fish, shrimp and sausage and stir until the shrimp is cooked halfway through, about 3 minutes.
Step 3Stir in the Creole seasoning, salt and black pepper. Add the gumbo base and marinara sauce to the pan and bring to a simmer.
Step 4Remove from heat and stir in the linguine noodles. Toss and plate. Garnish with a sprinkling of parsley and serve.