In a large, heavy-bottomed pot, combine equal parts of flour and vegetable oil over medium heat. Stir continuously for 20–30 minutes until the mixture transforms into a rich, dark brown roux.

Once the roux reaches the desired color, add diced yellow onion, celery, and green bell pepper to the pot. Sauté for 5–7 minutes until soft and fragrant. Add minced garlic and cook for an additional minute.

Stir in sliced andouille sausage, letting it brown for about 5 minutes to release oils and deepen the flavor.

Gradually pour in 6 cups of seafood or chicken stock while stirring. Scrape flavorful bits from the bottom. Add canned diced tomatoes and two bay leaves, then let simmer.

Sprinkle in 2 tablespoons of Cajun seasoning, salt, and black pepper to taste. Bring to a simmer, uncovered, for 45 minutes to 1 hour.

In the last 10-15 minutes of cooking, stir in the raw shrimp and lump crab meat until shrimp turns opaque and crab is warmed through.

Remove the bay leaves, taste, and adjust seasonings if necessary. Serve over rice, garnished with green onions.