Step 1

Heat the oil in a heavy skillet over medium heat. Gradually stir in flour, and stir constantly until the mixture turns 'peanut butter' brown or darker, at least 15 or 20 minutes. I use a large fork with the flat side to the bottom of the pan in a side to side motion. This is your base sauce or 'roux'. It is very important to stir this constantly. If by chance the roux burns, discard and start over.

Step 2

Once the roux is browned, add the onions, garlic, celery and bell pepper to the skillet, and saute for about 5 minutes to soften. Stir in the chopped tomatoes and fish stock, and season with the seafood seasoning. Reduce heat to low, and simmer for about 20 minutes, stirring occasionally.

Step 3

Season the sauce with hot pepper sauce and cayenne pepper (if using), and add the crawfish and shrimp. Cook for about 10 minutes, or until the shrimp are opaque.