1. Melt butter in large skillet. Add celery, onion, green pepper, and garlic; cook 5 minutes stirring occasionally. Sprinkle in flour. Cook an additional 5-10 minutes, stirring often, until vegetables are tender and roux is a medium brown color

2. Add chicken stock and tomato sauce; mixing well. Cook, stirring often, until bubbly and slightly thickened.

3. Add crawfish tails. Bring to boil. Reduce heat, cover and cook 10 minutes (or until crawfish are tender) on low heat, stirring occasionally.

4. Add salt, pepper, and cayenne to taste.

5. Add scallions and parsley. Simmer for a few minutes, covered, to blend seasonings.

6. Serve over rice.