In a large saucepan melt butter and sauté onion, celery and shallots until tender. Add garlic and cook 1 minute more. Stir in flour and stir constantly until golden brown. Add tomatoes and brown. Blend in stock and simmer 10 minutes. Add salt, pepper, cayenne,
Worcestershire sauce and crawfish, cook slowly 15 5o 20 minutes, stirring occasionally. Serve with hot rice