In a 2-gallon stock pot, melt butter over medium-high heat. Add onion, celery, bell peppers, tomatoes, garlic and bay leaves. Sauté until vegetables are wilted, approximately 3-5 minutes. Add crawfish tails and tomato sauce and blend well into mixture. Using a wire whip, blend flour into the vegetable mixture to form a white roux. Slowly add crawfish stock or water, a little at a time, until sauce consistency is achieved. Continue adding more stock as necessary to retain consistency. Bring to a rolling boil, reduce to simmer and cook 30 minutes, stirring occasionally. Add sherry, green onions and parsley and cook an additional 5 minutes. Season to taste using salt and cayenne pepper. Serve over steamed white rice using a few dashes of Louisiana Gold Pepper Sauce.