Peel and devein shrimp . Do not wash before peeling.
Make a qt of shellfish stock by placing unwashed shrimp shells in a pot. Add 2 quarts of water and 2 cups of white wine. Add 1 large onion, cut into 1/8, 1 carrot and 1 celery stalk cut into 1" lengths, 6 cloves of garlic cut in half, 2 bay leaves, 1/2 teaspoon of black pepper, i teaspoon of dried thyme and 1/2 lemon. Simmer for 1 hour then strain through fine cheese cloth strainer. Return stock to low boil and reduce to 1 quart.
If you do not have fish stock or the time to make it, substitute 16 ounces of clam juice and 16 ounces of vegetable broth. Mix together to form your stock.
In a two gallon heavy bottom sauce pan, heat oil over medium heat.
Using a wisk, add flour, stirring constantly until sauce like consistency is achieved.
Immediately add onions, celery, bell pepper and garlic. Sautee until vegetables are wilted, 3 - 5 minutes.
Add tomato sauce and diced tomatoes and blend well into the roux mixture.
Slowly add shellfish stock, a little at a time, stirring constantly until sauce like consistency is achieved. Cook 15 minutes, stirring occassionally.
Add stock should mixture become too thick.
Add shrimp, green onions and parsley and continue to cook five minutes.