Place all ingredients in a medium-sized dutch oven or pot. Add 6 cups of water, or enough water to cover the ingredients. Bring water to a boil over high heat, then reduce heat and allow mixture to simmer for 45 minutes. Skim off any foam on top of the pot, and then pour mixture through a fine-mesh strainer.

Melt the butter in a large fry pan or skillet over low heat. Whisk in the flour and cook over low heat, stirring frequently, for 18-20 minutes or until roux turns thick and medium-brown in color. (Note: It is very important to cook over low heat and stir frequently to prevent the roux from burning.)

Add the onion, celery, and green pepper, and cook over medium heat for 5-6 minutes, stirring often.

Add the Cajun seasoning, paprika, salt, minced garlic, and tomatoes; continue cooking over medium heat for another 2 minutes, stirring often.

Slowly whisk in the shrimp stock, stirring constantly, until the mixture reaches the thickness of gravy.

Mix in the shrimp and green onions; cover the pan and reduce heat to low. Cook for 8-10 minutes or until shrimp are cooked through.

Add the parsley and stir until well combined. Serve over steamed white rice; garnish with additional sliced green onions, parsley, and hot sauce.