In a black cast iron pot melt butter; add oil.
Over medium heat, sauté all seasonings until wilted, about 5 minutes.
Add flour and blend well.
Add tomato sauce and broth.
Add black pepper, white pepper and cayenne pepper.
Bring to a low boil then reduce the heat, and simmer, for 30 minutes.
Add shrimp, lemon juice, bay leaves, cover and simmer for 20 minutes longer.
Remove pot from the heat and allow to stand, covered, at room temperature for about 10 minutes before serving.
Serve over boiled rice.