Start by getting a large pot onto the stove on medium heat. Add in your butter, and melt it down. Once you begin seeing the butter foam, tilt the pot, and use a spoon to skim off just the top of the foam. Discard the foam. Return the pot back to the heat, and toss in the flour.
Stir the flour into the butter, and cook for about 5 minutes, stirring along the way. The flour will become blonde, then begin to darken a bit. Just be careful not to burn the flour.
Add in your onion, celery, bay leaf, garlic, carrot, and tomatoes, and cook for about 10-15 minutes in the roux, stirring along the way. Cook until the onions become translucent.
Once the onions turn translucent, add in the black pepper, salt, and cajun seasoning. Give a good stir, then add in your chicken stock. Stir well, and continue cooking on medium heat until the sauce thickens. I love this part and always have.
Once the sauce thickens, add in the crawfish tails. Stir again, and once the crawfish are warmed through, roughly 5 minutes or so, you are then ready to plate and serve.
Some like to serve rice on top, but my preference is to let the crawfish etouffee shine and serve on top of cooked rice.
So get a serving bowl ready, add in some cooked jasmine rice, and ladle on a nice pile of crawfish etouffee. Garnish with chopped parsley and dig in!