Before starting, prep all ingredients. Let's face it...it makes the whole process go more smoothly.
In a 10-quart stockpot, heat oil over medium heat. Add flour and stir to form a roux. Stir often, until roux is the color of peanut butter. Depending on cooktop, 10-20 min.
Add onion, bell pepper, celery, and garlic. Cook vegetables in the roux for about 5 minutes, stirring often. Add stock, filé, beer, bay leaves, Cajun seasoning, Worcestershire, salt and cayenne. Bring to a boil. Then reduce heat to medium and cook for about an hour. (I was in a hurry and only simmered it for 30 min. Cooking longer basically just helps to soften your veggies more.)
While mixture is simmering, cook chopped sausage enough to brown it. You could just toss it in with the seafood without cooking it, but I like the sausage a little browned.
Add all seafood and sausage to the pot. Cook till seafood is cooked through.
Get your pretty bowls out. Scoop some rice into the bowl. Then ladle the gumbo over that. Feel free to garnish with green onions, if you need even more flavor.